Backups and Disaster Recovery

8/14/2019 Backups and Disaster Recovery

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Backups and Disaster Recovery"What, me worry?" -- Alfred E. Neuman

One of the things that I harp on the most about when it comes to preventive

maintenance and system care, is the importance of regular, reliable data backup. Nomatter how well you treat your system, no matter how much care you take, you cannotguarantee that your data will be safe if it exists in only one place. The risks are muchgreater than most people realize.

How important is your data to you? You can respond to this question with words, butthe steps you take to protect your data are the real answer. I find it troubling when

people lose large quantities of data--because they have no backups--and then they getvery upset, talking about "how important that data was!" If it's important, why wasn'tit backed up? If it matters enough to get upset over losing, it's worth protecting, and

backups are an essential part of data protection.

There are many reasons that people neglect doing backups:

They don't understand how important they are, because they haven't had adisaster happen to them (yet).

They don't know how to do them.

They forget to do them because they don't have a routine for doing backups.

Doing the backup is a time-consuming chore and they can't be bothered.

This chapter takes a full look at the matter of backups, and discusses how to do them,how to set up a backup program, and what to do in the event of a disaster. Part of the

focus is on making backups easy to do so that you will remember to back up regularlywithout it taking an inordinate amount of time and energy.

Warning: Recent research has uncovered a potential problem with corruption ofshort file name aliases when restoring files with long file names using some

backup software. This phenomenon is discussed in the article Xcopy Xposed, whichfocuses on the problem as manifested when using the Xcopy command. You shouldcarefully factor this potential risk into your selection of a backup methodology.

A Mental Exercise To Underscore the

Importance of BackupsMost unfortunately, there are some things that people only take seriously after theyhave experienced personally the pain that results from not taking them seriously.Backups definitely fall into this category. Most people are relatively nonchalant aboutthem until disaster strikes--thereafter, they are much more diligent about backups (butafter the damage is done.) Despite the difficulty in getting people to learn from others'mistakes, I'm stubborn, so I will try anyway in this section. :^)
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Here's a mental exercise that you can do to help you understand how importantbackups are. Take a look at your PC and think about what is on it. Think about yourdata and your programs. Consider how much time it took to create the data, and to setup and tweak your PC so that it works the way you like. Now imagine that onemorning you go to your desk and the PC has vanished without a trace. What will you

do?

Let's suppose you had insurance on the hardware, and a week later a new PC showsup at your door with a fresh new, clean hard disk. Now what? Most people who askthemselves this question seriously, begin to take backups much more seriously.(Fortunately, for most people the exercise is only a mental exercise, but don't think itcan't happen to you in the real world.)

Recovering from a disaster such as a total disk crash or theft of a PC box can be avery traumatic event, much more than most PC users realize. This is true even if

backups exist; when they don't exist the situation is much, much worse. The pain of

recovering from a disaster is almost always very high, and the cost is primarily in thetime required to recreate the lost data. For even a small business, this can run into thethousands of dollars very quickly.

If you still aren't convinced, consider this report from the University of Texas Centerfor Research on Information Systems. Of the companies that lose their data in adisaster:

90% are out of business within two years...

Nearly 50% never reopen their doors at all after the disaster!

The Risks To Your Data If you do any sort of reasonable amount of computing, it is only a matter of

time before you some day need access to backups of your data or programs.There are many different risks to your data; most people just think of theinfamous, dreaded disk crash. This is a real risk due to the technology used indata storage, but there are many other ways that you can easily lose data onyour PC. In fact, the list of risks below is far from exhaustive, though it coversthe most common problems.

Some backup methods protect against all of the risks below, while some protectonly against one or a few of them. See this section for a comparison of the risk

protection offered by various backup methods.Hardware Failure

The risk of hardware failure is the most commonly talked-about reason to performbackups. Indeed, nothing will jolt someone into realizing the importance of backupsmore than an unrecoverable hard disk failure. Since the hard disk stores your main

programs and data, it is the hardware whose failure hurts the most. It is also what getsthe most attention, and rightly so.
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However, there are other hardware problems that can cause permanent data loss, andsome of these can be rather hard to figure out, since they don't seem like they should

be responsible for the problem. Here are just a few:

Memory Errors: With so many systems today running without error detectionor correction on their system memory, there is a chance of a memory errorcorrupting the data on the hard disk. It is rare for it to happen, but it doeshappen.

System Timing Problems: Setting the timing for memory or cache access tooaggressively, or using a hard disk interface transfer mode that is too fast for thesystem or device, can cause data loss. This is often not something that willgenerally be realized until after some amount of damage has been done.

Resource Conflicts:Conflicts resulting from peripherals that try to use thesame interrupt requests, DMA channels or I/O addresses, can cause data to

become corrupted.

Power Loss: Losing power at the wrong time, such as when you are doingsensitive work on your hard disk, can easily result in the loss of many files.

Software Failure

It is possible for data to be lost due to software bugs, or even just poor softwaredesign. For example, a program might have a problem where it crashes upon saving afile. Many programs, when saving a file over top of an older file with the same name(such as when you select "Save" to update the current document you are working on)will first save the new file under a temporary name, and then rename it to the correctfile name when the save is completed. But others may remove the old file first, so that

if the software crashes during the write process, the old file will be lost as well.Some software bugs may be even more damaging, even causing the loss of filesunrelated to them. This doesn't happen very often, fortunately.

File System Corruption

There are many ways that the file structures used to contain programs and data on thehard diskcan become damaged. In some cases, this corruption can result in data loss,especially if the disk is not maintained properly and the file system scanned on aregular basis.

Accidental Deletion

Since computer users are human, they make mistakes. One of the most common isaccidentally deleting files from the hard disk. There are many different protectionmechanisms and "undeletion" utilities that can help recover from this, but sometimesyou delete a file and then remember a few days later that you really need it, and in thissituation a backup is often the only thing that can save you.

There are other ways that you may accidentally delete files, maybe without evenrealizing it. Let's suppose that you have twenty files named MEMO01.DOC through
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MEMO20.DOC in a directory, and you want to move them to the directoryC:\OLDMEMOS. So you type:

COPY MEMO*.DOC C:\OLDMEMOS

DEL MEMO*.DOC

But let's suppose that you made a mistake and the C:\OLDMEMOS directory doesn'texist, or you spelled it wrong when you created it. If this is the case then the copycommand above will not be able to copy the files to a C:\OLDMEMOS directory.Instead, it will interpret the "C:\OLDMEMOS" as specifying the name of afile insteadof a directory, and will copy the contents of all twenty files to a regular file named"OLDMEMOS" in the C:\ root directory. The end result will be a single filecontaining the data in each of the 20 files, concatenated end-to-end. (You may be ableto recover from this if these are plain text files, but otherwise you are in trouble.)When the "DEL MEMO*.DOC" command is executed, it will remove all the filesfrom the directory they started in. You may not even realize that this is happening. Of

course being careful can avoid this sort of problem (be sure of what you delete!) but abackup can save you from the occasional accident.

Accidental deletion can occur even within a file. In creating this web site, I startedfirst with a very large, single document. On more than one occasion, I deleted sectionsof the text that I thought I didn't need, and was glad that I had archived older copies ofthe file that I could refer to, to restore the parts that I found out I actually needed lateron.

Virus Infection

Viruses can easily cause the loss of data, in many ways. This includes loss caused

directly by the virus and also program damage that results from efforts to removeviruses from a system.

Theft

Many PC users don't consider the possibility of theft as a danger to their data(although most people who use notebook PCs certainly do!) Even for desktops, thereis always the risk of the entire PC box disappearing one day if you have a break in, forexample. It is important to keep this possibility in mind, as some kinds of backups donothing to protect against theft. To my knowledge, insurance that covers theft ofcomputers will allow you to replace the system, but cannot pay to recreate lost data.

Sabotage

Generally applicable only to PCs in the work environment, sabotage by disgruntledemployees is a growing problem. A carefully-constructed backup program is the only

protection against a knowledgeable but angry person who is determined tointentionally cause data loss (and sometimes, even backups aren't enough.)

Natural Disaster


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Fire, flood, earthquake, mud slide, hurricane, lightning strike, you name it: all canresult in the destruction of your PC and everything on it. For many people getting

back their data will be the last thing on their minds when this happens, of course. Forothers, getting back up and running on a PC may be something they need to do rightaway. Also remember that insurance may cover the PC, but will not cover the data

that is on it.

Backup Methods, Devices and MediaThere are many different methods that you can use to back up the data on your harddisk. The primary difference between these methods is the device and medium that isused to store the backup. Different media have different characteristics, such ascapacity, speed, ease-of-use, universality, etc. This section takes a look at some of thedifferent choices you have for backing up your hard disk.

Media Size Matching

One very, very important factor to consider when looking at backup alternatives, ismatching the size of the backup medium to the amount of data you need to backup. Ashard disks continue to increase greatly in size, it becomes more difficult to find

backup solutions that can handle the entire contents of a PC using a reasonableamount of media. It is essential that the size of the backup medium be matched to thesize of the data being backed up.

It is tempting to ignore this issue as unimportant, but my experience (and that ofothers) is very clear: the more disks or tapes it takes to perform a backup, the lesslikely it is that they will be done on a regular basis. The reason is simple: when ittakes a lot of media to back up the disk, backup becomes a chore, and when it

becomes a chore, people avoid doing it.

In fact, the best situation of all, and one that I recommend, is a backup solution wherethe entire contents of the hard disk can be stored on a single backup tape or disk. Whatthis buys you is the ability to do unattended backup. You start the backup, and thenleave to do something else. When you return, the backup is done. If the contents won'tfit on a single cartridge, you have to intervene at some point to change media. Thischanges backup from something simple to something complicated. Don'tunderestimate capacity when comparing backup solutions.

Since you don't always need to back up the whole hard disk at once, a backup unit that

can't hold the entire hard disk, but can hold most of it, will normally suffice. If youcan store half the hard disk on a single cartridge, you can do unattended backups ofhalf the drive at a time. Less ideal than doing the whole system at once, but still quitetolerable, and you maintain the ability to do unattended backup.

Let's take an example look at the Iomega Zip drive. This is a removable storage devicewith a capacity of about 100 MB. A very useful drive, it stores data reliably, and if the

parallel version is used, can be extremely handy for transferring information between


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PCs. However, it is also advertised as being great for backup. Well, I guess it dependson your system, but mine has over 3 GB of programs and data on it. Many peoplehave over 1 GB on their hard disks. For this amount of data, the Zip drive is notsuitable as a backup device. Backing up 3 GB of data onto Zip disks would take 30disks (costing several hundred dollars, mind you) and the disk swapping would be

annoying enough to guarantee that the backup was rarely if ever done. A 100 MBdrive can be useful for archiving parts of a large disk, but it isn't a solution for ageneral backup, because you can't even do half or even a quarter of a modern harddisk on such a unit.

Removable Storage Drives

In the last few years, a whole new class of storage devices has sprung up and becomevery popular--removable storage drives. While these have existed in various forms formany years, it is only recently that they have taken the market by storm. Their

popularity rests in their ability to provide removable storage at a reasonable price and

with good performance. Many of these drives are also very suitable to use forbackups.

There are so many different drives, and they differ in so many different ways that acomplete look at all of them (at least one that would be fair) is far beyond the scope ofthis section. (I hope to add a full chapter in the Reference Guide that will look at thesedrives at some point in the future.) Looking at the various characteristics of thesedrives, we see that many of them are suitable for backup purposes, but some really arenot. The drives fall into several categories, which I will look at briefly:

Large Floppy Disk Equivalent Drives: This would include the Iomega Zipdrive, Syquest's EZ-135, the LS-120 120 MB floppy drive, and a few others.

These devices are suitable for backup only if you have a small hard disk, orhave the diligence and patience to do attended backups or large numbers of

partial backups. As hard disks increase in size to 4 GB and beyond, trying to dobackups to a device that is only a little more than 100 MB becomes impractical,and quite expensive. The reliability of these devices is quite good, althoughthey are proprietary and not very universal. Their performance is general poorto average.

Removable Hard Disk Equivalent Drives: This category includes devicessuch as Iomega's Jaz drive, Syquest's SyJet, and various kinds of phase-changeand magneto-optical drives. These are much more suitable for use as backup

devices due to their larger capacity, but even here things are becomingstretched, since even 500 MB to 1 GB is becoming inadequate for unattended

backups. These drives have generally much higher performance than thesmaller drives, and much higher price tags to go with them. Reliability isusually good, and the drives are still proprietary.

CD-Recordable: These are write-once read-many drives with a capacity ofabout 650 MB, described in detail here. Despite the fact that the disks are not
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reusable, some people actually use them for backup, now that the price of blankdisks has gone down to around $3 a piece or so. This is a very expensive way todo backups; it does give you the advantage of being able to refer back tohistorical snapshots of your disk for a long time, but you're really going to payfor it. The cost will discourage most people from doing backups often enough.

The capacity is on the small side at 650 MB. One great advantage is that thebackups are readable by any CD-ROM drive. I do not recommend CD-R forroutine backups, because the cost of media over time is excessive. This willdiscourage you from doing backups on a regular basis, which is the last thingyou want.

CD-Rewriteable:This drive is really in the same category as the removablehard disk equivalents listed above. CD-RW has a lot going for it as ageneral-purpose medium, because of its flexibility: its media are reusable and it canalso burn CD-Rs that play in most CD-ROMs or audio CDs as well. But as astrictly backup medium, I don't think it has a lot to recommend it. It is not

inexpensive, the capacity is only so-so at 650 MB, and the CD-RW disks areessentially proprietary since only newer CD-ROM drives will read them. It'scertainly usable for backup, but other options may be better if you don't needthe other advantages of CD-RW.

Removable Hard Disks

An interesting backup method that most people don't know about is the use ofremovable hard disk drives. Here's how it works. You purchase a special kit thatincludes a mounting kit that you install into an external drive bay in your case. Youalso get special adapters (sometimes called carriers) that attach to regular, internal

IDE hard disks. This allows you to insert and remove these internal disks through anexternal drive bay, turning your regular IDE hard disk into a sort-of removable drive.It works in a way similar to how a removable car stereo works.

To allow for backup flexibility, you will want to have more than one drive. One wayto handle this is to buy several identical hard disks and put them all in carriers, so youcan swap them easily. Or, if your BIOS supports hard disk autodetection, you can usedifferent types of disks and the system will reconfigure to use whatever is currently

placed in the drive bay each time you reboot.

This type of system, even though it sounds strange, can actually be a quite viablebackup solution. While it seems that it would be overly expensive to buy hard

disks just for backup, the price per gigabyte of hard disks is actually verycomparable to drives such as the Iomega Jaz--in many cases, much less. This isespecially true if you buy slightly older, smaller disks. A removable hard disk alsohas the following other advantages: very high performance, random-accesscapability, standard interfaces and exchangeability, and excellent reliability.

This type of scheme has some disadvantages as well of course. Compared tosomething like tape, you lose the ability to buy additional backup media cheaply; to
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add 2 GB of more backup storage on a 2 GB tape drive costs about $25; with thisscheme it would be several times more. Hard disks are also fragile; if you drop themthey can be damaged. (Note that both of these disadvantages also apply to several ofthe larger removable-storage drives.) The final and perhaps biggest drawback of thistype of scheme is that the disks can only be removed when the power is off; you can

switch media in a standard removable drive on the fly with the power on, but not here.

In-Place Hard Disk Duplication

One backup solution that some people who have more than one hard disk use is to setup their system so that they use one hard disk for their programs and data, and theother one as a backup. They then copy the contents of the one hard disk to the otheron a regular basis, using a file- or disk-copy tool.

This scheme is interesting and can be useful in some ways, although it hassomesevere limitations as well. Its advantages are that it is simple, and that it isautomatable; you can set it up to do this on a nightly basis and know that everything

on your hard disk will be duplicated automatically without you having to remember todo anything. This increases the chances that the backup will be done. The

performance of the disk-to-disk copy will be very high, and the cost is pretty muchreasonable.

The drawbacks of this sort of a scheme however are significant. First, it doesn'tprotect against very many of the risks to your data--it is not going to help muchagainst theft, fire, sabotage, many types of viruses, and even some types of hardwarefailure. Second, you can only have a single backup, which makes the whole systemvery vulnerable--if you make a copy of the whole disk every night, what happens ifyou only notice a problem three days after it wipes out some of your data? Finally, the

temptation is large to use the second drive for more data and discontinue the backupprocedure when the first disk gets filled up,.

Overall, I don't recommend in-place hard drive duplication as astandalone backupprocedure. It can be useful when supplemented by a removable backup system.

Network Backup

For PCs on a network, backup over the network is a viable alternative to usingremovable drives. This type of scheme is sometimes used in small- to medium-sizedas a way of protecting PCs without the expensive of tape drives or removable storage.The idea is fairly simple: copy data from one PC to another over the network.

Duplicating each PC's information provides a way to protect each individual PC.In a way, this type of backup is most similar to in-place hard disk duplication in termsof how it works. It is simple in the same way, and can be automated. It addressessome of the concerns about that method: there isn't the same single point of failure interms of virus attack or hardware failure. However, depending on the location of thetwo PCs, theft, disaster and sabotage can still be a big problem: if the two PCs aresitting on different desks in the same office, you haven't gained much to protect


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against these threats. Also remember that file-infector viruses can travel over anetwork.

An even better use of the network, becoming popular in many corporateenvironments, is to use a centralized removable storage backup device in conjunctionwith the network to back up all the PCs automatically. Consider a local-area networkwith 10 PCs, each containing 1 GB of programs and data, connected to a server with 5GB of storage and an 8 mm tape drive with a capacity of 10 GB. Using compression,this drive can hold the entire contents of the network on a single tape, and usingnetwork backup software and the right operating system, the network can be used to

back up all the PCs every night, automatically. This is an excellent backup system thatallows the desktop PCs to reap the benefits of the tape backup unit without everyonehaving to remember to do backups.

File Archiving

A supplemental backup method that I use, and recommend that others consider, is

simple file archiving. What I mean by this is simply making backup copies of filesthat I use periodically, in case I need them later on. When I am working on a largedocument over a period of weeks or months, this document is changing far more oftenthan the other files on my hard disk. I want to therefore back it up more often, in caseI make a mistake in the document or my program decides to munch it. It's not

practical to break out my tape drive several times a day, so I do this by simplycopying the file to another location on the hard disk once in a while.

This is a limited form ofin-place hard disk duplication, which is not a completebackup solution. In fact, this system only really protects well against accidentaldeletion, which is why I call itsupplemental. However, it can still be very useful to do

this. A simple way (which is what I have done) is to create a directory on your C:drive (or wherever) called BACKUP, and then create a simple batch file containingthis line: "COPY %1 C:\BACKUP". (Batch files are files that contain commands thatare executed when you run them.)

Save the file as say, BU.BAT, and store it in a directory that is in your file executionpath, such as C:\WINDOWS\COMMAND. Then, to back up FILE.TXT you just type"BU FILE.TXT". Make sure to clean the directory out periodically.

Comparison of Backup Method Data Risk Coverage

Some of the backup methods and devices described in this section do a much better

job than others of protecting against the risks to your data. The table below shows ageneral summary of how the various methods stack up in terms of protecting you fromthe hazards that threaten your valuable data. Remember that this is just a generalguideline; also remember that some of these risks are much more common than othersare, depending on how you use your PC:

Data Risk FloppyDisks

TapeDrives

RemovableStorage

RemovableHard Disks

In-PlaceHard Disk

NetworkBackup

FileArchiving
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Drives Duplication

HardwareFailure

High HighModerate to

HighModerate to

HighModerate High Low

SoftwareFailure

High High High High Moderate High Low

File SystemCorruption

High High High HighLow to

ModerateModerateto High

Moderate

AccidentalDeletion

High High High High High High High

VirusInfection

Moderate HighModerate to

HighModerate Low

Moderateto High

Low toModerate

Theft High High High Moderate toHigh

None Low toModerate

None

Sabotage High High High High Very Low Low None

NaturalDisaster

High High High High NoneLow to

ModerateNone

Comparison of Backup Method Characteristics

In order to help you understand how the various backup methods compare to eachother and help you make a decision about which one makes the most sense for you, Ihave enclosed the chart below. It evaluates the various backup methods in severaldifferent important general areas. These areas are:

Capacity: How much does the medium store, relative to current average harddisks? Is it likely that an average user's hard disk will fit onto one or maybe two

pieces of media for the device/method?

Automatability: How possible is it to fully automate the backup so that ithappens without any user intervention at all?

Minimized Startup Cost: How well does the method minimize startup costs

for hardware or software?

Minimized Media Cost: Does the method allow additional backups at areasonable cost?

Expandability: How possible is it to do more backups, or add additionalbackup media if needed?


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Reliability: In general terms--because this varies widely based on the type ofdevice for items such as tape drives--how likely is it that if you have a disasterand need to restore from the backup, it will work for you?

Simplicity / Convenience: How easy is the method to use? Is there anydifficulty associated with the method that would tend to discourage doing

backups?

Universality: How common is the hardware used for the method? If youneeded to use the device in five years, how likely is it that you could findsupport or additional media for it?

Performance: How fast is the hardware and software used for the method?How much time will it take to do a backup?

Routine Potential: In general, how likely is it that, using this method, someoneis likely to settle into a backup routine and stick with it?

Here is the chart; for all items, "High" is better and "Low" is worse (I inverted the costitems so that high had a better meaning and low worse, to keep things consistent,sorry if it is confusing):

CharacteristicFloppyDisks

TapeDrives

RemovableStorageDrives

RemovableHard Disks

In-PlaceHard Disk

Duplication

NetworkBackup

FileArchiving

CapacityVeryLow

HighLow toHigh

High High High --

Automatability Low Low Low Low High High High

MinimizedStartup Cost

VeryHigh

Low toHigh

Low toModerate

Moderate Moderate High Very High

MinimizedMedia Cost

LowModerateto High

Low toModerate

Moderate Very LowVeryHigh

Very High

Expandability High High HighModerate to

HighLow

VeryHigh

High

Reliability LowLow toHigh

Moderate toHigh

Moderate toHigh

HighVeryHigh

Very High

Simplicity /Convenience

ModerateModerateto High

Moderate toHigh

Low Very High Moderate High

UniversalityVeryHigh

Low toHigh

Low toModerate

Moderate High High High

Performance Very Low to Low to Very High Very High Moderate Very High


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Low Moderate High to High

RoutinePotential

VeryLow

Moderate Moderate ModerateModerate to

HighHigh Very High

Note: For a more complete picture on how the various methods stack up, makesure to check out how they cover the various risks to your data as well. Many of

the methods that look very attractive based on what you see above actually don'tprotect against enough of the data risks that you use backups for, to make them trulyviable options.

What To Back UpTo ensure that your backups are performed properly, in a way that ensures that youare protected without taking so much of your time that they become a chore, you mustdetermine what files to back up and how often to back them up. Some files will need

to be backed up more often than others. This section takes a look at what files you willwant to include in your backup routine, and also the ones you will usually want toexclude.

Full, Selective and Incremental Backups

There are several different ways that we can select files for backup. The way that youwill want to use depends on how you use your system, how often your files change,and your chosen backup method. Many people will in fact end up using a combinationof these different techniques:

Full Backup: Nothing complicated here, a full backup is done

by selecting all the files on the hard disk for backup.Onlyspecial files that should not be backed up at all are leftout. This is the simplest type of backup, and yields the mostcomplete backup image, but it takes the most time and mediaspace to do.

Selective Backup: In a selective (or partial) backup, youselect specific files and directories to back up. This type ofbackup gives you more control over what is backed up, at theexpense of leaving part of the hard disk unprotected (unless of

course, you simply do another selective backup later on thatcovers the area you skipped the first time). Selective backupsmake sense when some files are changing much more rapidlythan others, or when backup space is limited, although in manycases doing an incremental backup is better and easier.

Incremental Backup: If you perform frequent backups, asyou should, you may find yourself backing up the same files
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over and over, even ones that do not change over time.Instead, you may want to consider a mix of full backups andincremental backups. An incremental backup is one where onlythe files that have changed since the last backup are selected.It is like a selective backup, but the files are selected based onwhether they have changed recently or not, instead of anarbitrary selection based on directory or file names. This givesthe time- and space-saving advantages of a selective backupwhile also ensuring that all changed files are covered.

Incremental backups are supported by most decent backup software. They work usingthe archive bit that exists for each file and directory. The backup software looks at this

bit to determine what files have been changed since the last backup, selects them forbackup, and then clears the bit for all the files it backs up. If any files are changed, thesoftware sets the bit again so on the next incremental they are again selected, and so

on. You must rely on this bit being managed properly, and I don't always like to dothis.

Warning: Programs that change files are not required to set the archive bit. Mostwell-behaved software will do this, but you cannot absolutely guarantee that all

files changed since the last backup will be caught by an incremental selection.

Which type of backup you do depends, again, on what is important to you, in terms oftime, media cost, and also ease of restoration.Restoring a system that uses incremental

backups can require more steps, as first the full backup has to be restored and then theincrementals, one after the other. You also don't have the redundancy (just in case you

need it) that you have when your backup scheme uses only full backups. If you can fita full backup onto a single media set and it doesn't take too long to do, I still preferthis over incrementals, for this reason. It's just more secure to know that everything ison one tape. The scheduling of backups is discussed here.

Backing Up Programs and Data

Most files on a typical PC can be broken down, loosely, into being either programs ordata. These differ of course in many ways, but not least is in how they should beconsidered for backup.

In general, data files should always be backed up. These are the fruit of your labor,

and cannot be replaced! Every backup should include all of your data, either via a fullbackup of the entire hard disk, a selective backup that includes the directories wherethe data is, or an incremental backup. (Having all your data in a handful of directoriesinstead of scattered all over the hard disk is useful, for this very purpose).

Programs are a somewhat different story for two main reasons: first, they are static,meaning once installed they do not change (with a few exceptions). Second, they arerecreatable; if your Microsoft Office directory gets wiped out, you can reinstall it from
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your original CD-ROM disk. The combination of these characteristics suggests thatbacking up programs is less important than backing up data, and this is true. Programsdo not need to be backed up as often as data does.

However, you should also remember that setting up and configuring a PC today takesa considerable amount of time. Tweaking all the operating system settings, installingall the software, and modifying parameters to get everything working the way youwant can take the better part of a weekend. While you can reinstall Windows 95 andall of your applications if you have to, this is not something that is going to be fun todo. You will also have the problem of remembering what you changed from thestandard defaults. For these reasons, installed programs should definitely not beignored when looking at backup.

Note: Some PCs ship with their software preinstalled on the hard disk and nooriginal disks or CD-ROMs! This is a poor practice and I recommend that people

avoid buying from companies that do this, since it makes it very hard for you to

reinstall software if you need it in case of disaster. If you have no original disks, yourinstalled programs should be treated as just as unrecreatable as your data. Incidentally,many PCs that come only with preinstalled software have utilities that will let youcreate install disks from what is stored on the hard disk, sort of a "reverse install";consult your owner's manual.

I believe that a full backup of the entire hard disk is still the best type of backup, forthe simple reason that it is the safest and easiest way to get you back where you were

before a catastrophic data loss--and that is the exact purpose of backup. If you don'thave the backup capacity to do the whole hard disk, then consider a combination of

full and incremental backups, which will preserve any changes you make to yourprograms while saving media.

Files Not to Back Up

There are some files that should never be backed up. The main reason is that somefiles do not contain anything that would matter if they were lost. Another reason isthat some files are representations of programs or data that are better backed up in adifferent form. While virtually all regular files should be backed up, in most cases thefollowing kinds of files should be excluded from routine backups:

Swap Files: A swap file is a large file that is used by theoperating system for virtual memory. When the system needsmore memory than actually exists in the PC, it creates a virtualmemory space and applications "share" the real memory byswapping pieces of memory to the hard disk. The swap fileholds these pieces; the process is described in much moredetail here. This file can be quite large, sometimes exceeding50 MB in size depending on the system. Since it does not
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contain any real data, but rather is a placeholder forinformation in memory while the PC is running, there is nopoint in backing it up.

Compressed Volume Files: If you use volume-based disk

compression, the compressed volume that you see mounted asa drive letter is stored on the host disk as a single file calleda compressed volume file or CVF. All the files on thecompressed disk are in this file. If you use compressedvolumes, the files on them should be backed up individuallyfrom the compressed volume. The big CVF file on the host diskshould not be backed up, since it contains the sameinformation but in a way that is much more difficult to restore.

Most newer software will in fact automatically deselect the items above, unless youoverride and tell it you want them included anyway. Many types of backup software

will also let you select classes of files, by file type, that you want to exclude forwhatever reason.

How To Back UpWhile backing up your data is in some ways a simple matter--"just do it!"--there are infact some special techniques that can come into play to make backups more effectiveand less of a hassle. This section takes a look at specific techniques and considerationsfor performing backups, some of which you might not think of. This includes adiscussion of backup timing, scheduling, media storage, and how to ensure that your

backups work, and will protect you in the event that you need them.

Backup Timing

Selecting a time of day to perform backups is a matter of personal choice. It depends,as usual, on how you use your PC, and also on how long it takes for you to perform

backups. Most people prefer to do unattended backups, and therefore, set theirbackups up to run when they are not around. The most common times to run backupstherefore are:

Overnight: My personal choice, and the preference of manyother people, is to start a backup before going to sleep, have itrun overnight, and then see the results in the morning. Thismakes sense because the PC isn't being used, and a fullbackup of a loaded system, including time toperform verification, can take several hours.

During the Day: If you work during the day you can set upyour home machine to perform backups while you are at theoffice. This is really not much different in concept from the
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overnight backup; both use slack time where the PC isn't beingactively used, to perform backups. I don't do this myselfbecause I run routine maintenance on my PC during the day.

Warning: I only recommend backup overnight or while away from home for

backup systems that are established and known to work well. Do not attemptyour first backup on a new drive overnight, because if there is some problem, youwon't find out about it until 8+ hours later. A misconfigured or defective tape drivecan sometimes "shoeshine", meaning it constantly runs the tape back and forth overthe surface of the tape head. This can be very damaging if allowed to continue forhours at a time!

Most backup software can be set to run at a specific time and day of week as well, ifthis is convenient for you. Remember to watch out forinterference from othersoftware.

Backup SoftwareAn important part of the backup puzzle is using the right software. The difference

between good and mediocre backup software can be the difference between backupsthat are reliable and easy to use and ones that are not. The difference betweenmediocre software and bad software can be the difference between backups thatrestore properly when you need them to, and those that leave you high and dry!

This is a hardware site and I am getting pretty far afield with this long look at backupas it is, so I am not going to try to get into too many specifics on backup software(which I could write quite a lot about). You have to carefully compare the different

packages out there and get one that meets your needs, much as with any other piece ofsoftware. The various features of backup software can be confusing however, so I willlist below the types of capabilities you will want to look for in backup software, tohelp you make a good choice when you look for a package.

Beware that here, as in many other places, you sometimes only get what you pay for.Many backup devices ship with basic backup software, provided as a courtesy by thehardware manufacturer. In many cases these are functional but stripped-downversions of commercial packages. They will usually work, but may not be nearly asfull-featured as a package you would buy at the store. The best thing to do is to tryany software that comes with your device; if it meets your needs then you don't needto buy anything else.

The following are abilities or features that you may want to consider carefully whenlooking at PC backup software (not listed in any particular order):

Wide Device Support: Backup software varies significantlyinits ability to support backup devices. Generally speaking, it ismore difficult to find software support for newer devices thanwell-established ones. Some software companies will make
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software updates available for their users to provide expandedsupport as new drives hit the market; others will not. Doremember that while support for more devices gives you moreflexibility, ultimately the only device you reallyneed supportfor is the one that you are actually using.

Operating System Support: The software should support allof the features and requirements of the operating systemunder which it runs. This means, for example, that Windows 95software should have full support for long filenames, backup ofthe Windows 95 Registry, and backup ofFAT32 partitions.

Backup Type Selection: All good backup software will let youchoose between doing full, selective and incremental backups.Better ones will let you select files and directories based onsearch strings or patterns.

Media Spanning: The software should provide proper supportfor backing up to multiple pieces of media in a media set. So ifyou did a backup to Zip disks and the data took up 250 MB, thesystem should prompt you when it is time to switch disks, etc.Strangely, some poor backup software has problems with this.

Disaster Recovery: A very important feature, and one that isoften found only on more expensive products (as opposed tothe freebies that come with many tape drives) is supportfor automatic disaster recovery. With this type of software,

sometimes called one-step recoveryor single-step restore orsimilar, a floppy disk is created with a special recoveryprogram that will let you restore your system simply. Withoutthis feature, you often have to reinstall the entire operatingsystem before you do a restore, which can cost a lot of timeand cause a lot of problems.

Scheduling and Automatic Operation: Depending on howand when you do your backups, it can be very helpful to havethe software run automatically at a preset time. Most of

today's software will support this. Backup Verification: Every decent backup package will allow

you to enable a verification mode. When active, the softwarewill read back from the tape every file that it backs up andcompare it to the file on the hard disk, to ensure that thebackup is correct. This is important to ensure that yourbackups are viable.
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Compression: Good backup software will give you the optionof enabling software compression, possibly at various levels, toenable you to save space on your backup media.

Media Append and Overwrite: You should be able to set the

software so that you can control easily what happens when thesoftware starts a backup of a tape that already contains abackup set. You should be able to tell the software to alwaysappend to the tape, always overwrite it, or prompt you eachtime to let you select.

Tape Tools: If you are using a tape backup unit, the backupsoftware will allow you to do things like formatting, rewinding,retensioning or viewing the catalog on your tape. The tapedrive may come with software that does this for your particularmodel; it's much easier if the backup software supports these

tools also, however.

Security: Better software packages will let you password-protect a backup set so that the password is required to viewor restore from the backup image. (Be very careful beforeusing something like this, you don't want to lose thatpassword!)

Backup Configuration Profiles: You may want to dodifferent types of backups at different times. For example, youmight have a bunch of compressed ZIP files on one drive and

want them to be backed up with tape compression off (since itwon't do anything anyway) while your regular files on anotherdrive are backed up with compression. Good software will letyou store different profiles for different types of backups tosave you from having to change things every time.

General Quality Issues: You should find out about thegeneral nature of the software. Does it work well? Is it buggy?Are people having problems with it? What is the warranty?What is the upgrade policy of the manufacturer? USEnet can

often be of assistance here.Software Conflicts

When performing backups in a multitasking operating system, it is necessary to bewary of possible conflicts between the backup software and any other software thatmay be running simultaneously. Any programs that are running in the background thatmight write to files or directories on the disk can confuse the backup software,especially when it goes to verify the files it has backed up, because it may find
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different files in some directories at the end of the backup compared to what was thereat the beginning.

Another problem is with files that are locked due to another program having exclusiveaccess to the file. To prevent more than one application from changing a document atthe same time, many applications will lock them out so no other application can usethem. This can cause the backup software to be unable to back up these files.

If you are doing backups from a single-tasking operating system like DOS, you don'tgenerally have this concern (because you don't have multiple programs runningsimultaneously). However, watch out for TSR (terminate and stay-resident) programsthat might be in memory at the same time as your backup software. If you schedule

backups to run at a pre-set time while you are away, you may have a more difficulttime of ensuring that nothing else is running at the time the backup starts.

The solution to avoiding these problems is, in most cases, to simply turn off othersoftware when you are doing a backup. This is what I do. I close all applications

before I begin a backup, and make sure there is nothing running in the background (Iuse Windows 95). I also disable my screen saver, to ensure that it doesn't causeinterference (this can be done by going to the Control Panel, selecting "Display" andthen "Screen Saver"). Another advantage to doing this is that I ensure that the backupsoftware gets as much of the processor's attention as it needs.

Data Verification

After you have backed up your data to tape, you can feel confident that you have acopy of your data that you can use in the event that anything happens to your PC. Orcan you? If you're paranoid like me you might want an additional level of security tohelp you feel safe. This is easy to do, by using backup software that includes theability to perform data verification, and enabling the feature.

The idea behind verification is simple: after the files are backed up, the backupsoftware reads back the information from the backup media and compares it back tothe original files. This ensures that the backup just made is readable, and that the filesmatch what was just copied. I recommend that data verification be used, as it is asimple way of feeling more sure that your backups are working correctly. The onlydisadvantage is that it lengthens the amount of time that it takes to perform the

backup, but if you are backing up overnight or while away from the PC, this will haveno effect on you anyway.

There are two different levels of verification that you will sometimes find, dependingon the software you are using. The most secure level of verification isfull verification,where each and every file that is backed up is also verified by reading back from the

backup medium. A lesser type of verification issampling verification . Here, instead ofverifying everything that was backed up, a sample of what was backed up is read backand verified. This makes the verification take much less time, but of course doesn't donearly as good a job. Usually full verification is easier to find on most software thansampling.


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The ultimate in backup verification is doing a test restore, but this takes both time andsome spare hardware. If you have an extra hard disk or PC, you can take your backupset and try to restore the backup to this machine. If it works properly, you can feelconfident that your backup will probably protect you when you need it.

Backup Compression

Most backup systems support some type of compression. The idea behindcompression is simple: to save space and allow the backup of more data onto a givenmedia set. Most software supports compression, and in fact many backup deviceseven quote their capacity on the assumption that compression will be used during

backup.

Normally there is nothing wrong with using compression, and in fact I use it myself inmany cases. You do need to bear in mind a few things, however:

Compressability: Not all files will compress equally well, asexplained in this section on hard disk compression. If you arebacking up a large number of files that are already in acompressed format, it may make sense to turn offcompression, since it isn't going to do much for you anyway.

Proprietary Formats: Each software program (or in manycases, family of software programs made by the samecompany) will use its own compression algorithm. This meansthat the tape written by one program may not be readable by adifferent software package. This is not normally a problemsince most people only use one package on one PC, but it is

something to bear in mind. The backup formats themselves arereasonably universal if compression is not used.

Processing Power Requirements: In order to write sometypes of backup devices, especially tape drives, it is necessaryfor the software to provide to the device a steady stream ofdata. This is because tape can only be written to when it isstreaming at constant speed. Compression algorithms taketime to run and can sometimes interfere with this steady flowof data, causing problems like shoe-shining (where the tapehas to repeatedly back up and restart sections of the backup).Compression should be turned off in most cases if doing thebackup on a slower PC or if it is suspected that compressionoverhead is causing problems.

Exaggerated Compression Ratios: Watch out for overly-optimistic estimated compression ratios. Many tapemanufacturers like to claim that their 1.6 GB tapes for example
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will hold 3.2 GB "with compression". In practice, I rarely if eversee any full disk volumes (as opposed to collections of certaintypes of files) that will compress at a 2:1 ratio.

Media Storage

Your data backups are exactly as safe as the physical media that contains

them. If you do a tape backup and then leave the tape lying on top of the PC

box, then you are partially defeating the purpose of doing backups. You will

give back the protection that tape offers against risks like theft, disaster or

sabotage.

Backup media should be stored in a safe place, away from the PC. In fact,

the word safe is appropriate, since a locked safe is the best storage

container for backup media. The use of a safe allows the media to be

secured from prying eyes and fingers while remaining in the same general

vicinity as the PC. A fireproof safe is an even better idea, for obvious

reasons. Just make sure you don't lose the combination. :^)

Depending on the type of backup media you are using, you want to make

sure that the storage environment is appropriate. For magnetic media such

as tapes and disks, you want to ensure that the storage area offers

protection from the hazards that threaten them, including temperature,

moisture, dirt, magnetic fields and the like. A plastic box on a sunny window

sill is definitely not a good idea.

Finally, pay attention to the matter of off-site storage. It is a good idea toensure that one or more of the backup media sets in the media rotation

system you are using is always be stored off-site. This is important to allow

for safeguarding against total disaster (tornado, hurricane, whatever).

Boot DisksA very important, but separate, part of your backup strategy should be the creationand maintenance of boot disks. These disks are used in the event of an emergencywith your system (they are in fact sometimes called emergency boot disks). They are

designed to enable you to quickly and easily correct large-scale software andoperating system problems with your PC, and to allow you to reconfigure or updateyour system without being totally dependent on the contents of your hard disk.

This section discusses boot disks and how they work, and provides details on how tomake and use them effectively.

Importance of Boot Disks


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You rely on your hard disk to boot your PC each day, but what would happen ifsomething happened to your hard disk to make it unbootable? There are manydifferent situations that can cause this to happen, ranging from hardware failure toerroneous operating system upgrades to virus infections. In addition to a backup ofyour data and programs, you need a backup of your bootable operating system so you

can start the PC even when something happens to your hard disk. This is whatemergency boot disks are for.

Typically, a boot disk will be used in the following situations:

Booting the System: In the event that your hard disk failsand is unable to boot, you can use your boot disks to start upthe system. This will allow you the opportunity to troubleshootand hopefully correct the problem with the hard disk.Sometimes a hard disk will be accessible after booting from afloppy disk, even if the hard disk itself will not boot. Without a

boot disk, you are dead in the water since you will be unable toeven start up the system at all.

Disaster Recovery: Ideally, the restore software for yourbackup media should be on an emergency boot disk. This willenable you to recover from a hard disk disaster and restoreyour system from your last backup media set(s).

Virus Detection and Disinfection: Many viruses, especiallyboot sector infectors, will automatically load into memoryevery time the hard disk is used to boot the PC. Once in

memory they will interfere with attempts to remove them fromthe system. To avoid this, a virus disinfection session shouldalways be done after a boot from a floppy disk that is known tobe clean and functional.

Hard Disk Upgrade or Installation: A new hard disknormally comes unformatted with no operating system on it,and therefore cannot be used to boot the system. The normalway to get the operating system onto the disk is to use a bootfloppy to start up the system and then transfer the operatingsystem files to the hard disk.

I strongly recommend that every PC owner have a set of boot disks for their system,for use in any of the above circumstances.

Boot Disk Contents

Depending on how you use your system, you may have one or several boot disks. Themain reason for this is that programs are getting larger and larger, and it can bedifficult to get all of the contents that you need onto one disk. In addition, many
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programs such as the Norton Utilities or backup software with disaster recovery, willvolunteer to create their own boot disks, sometimes called "emergency disks" or"rescue disks". These will normally use separate physical disks, and sometimesduplicate some of the information that is on your "homemade" disks. There is nothingwrong with this at all, as long as you don't end up with a ridiculous quantity of boot

disks.

Regardless of how many disks you have, you should always have duplicates of everyone in the set. The simple fact is that floppy disks have a high rate of failure, and youdo notwant to get a "Sector not found reading drive A:" error as you attempt to rebootto recover from some disaster.

If you have multiple boot disks, it isn't really necessary for every one of them to bebootable. ("Huh?") What I mean is that if you only have one boot disk that holds allthe files you need, you must ensure that it contains the operating system files that willlet you boot the system. If your boot disk set includes several disks holding items such

as your antivirus software or other files, they don't allneed to be bootable as long asyou have at least two disks that will let you boot the system.

Remember that especially with the operating system and system utilities files, youneed to put on the disk the programs that are appropriate to whatever operating systemyou are using. Putting a copy of DOS 6.22's FORMAT.COM on a Windows 95 bootdisk is pointless, because it will not run if the system is booted by that disk (which isDOS 7.x).

Here are some of the items that I think it is important for you to consider putting onyour set of boot disks:

Operating System: The boot disk (at least some of them)must be capable of booting the computer, of course. Thismeans creating a boot disk that contains whatever files youroperating system needs to boot up; see this section for moreon creating the boot disk itself.

System Configuration Files: Assuming you are using DOS ora DOS-based operating system like Windows, it's a good ideato include your CONFIG.SYS and AUTOEXEC.BAT files on theboot disk. You may want to rename them however, so thatthey aren't automatically used by the floppy disk when it boots

(since these files will contain lines referring to items on yourhard disk that may not work when booting from a floppy).

Hard Disk Partitioning and Format Utilities: You definitelyneed utilities on the boot disk that will allow you to partitionand format your hard disk if you need to. This means, at a veryminimum, including the programs FDISK.EXE, FORMAT.COMand SYS.COM on the disk. Make sure you use the versions
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corresponding to the operating system you put on the disk, orthe programs will give an "Incorrect DOS version" error and willnot run. If you have a copy of Partition Magic or a similarpartitioning utility, creating a floppy disk with this utility on itcan be veryuseful; follow the directions that come with thesoftware to create one.

CD-ROM Driver and MSCDEX: In order to allow theinstallation of CD-ROM-based operating systems, you must beable to access your CD-ROM drive. This requires two pieces ofsoftware: a CD-ROM driver and the file system extensionMSCDEX.EXE that comes with the operating system you areusing. Make sure both are included and that the driver isloaded in the CONFIG.SYS system file and MSCDEX.EXE in theAUTOEXEC.BAT system file.

Diagnostic Utilities: If you have diagnostic utility software onyour PC, including a copy on a disk can be very useful fortroubleshooting problems with your system. At a veryminimum, include SCANDISK.EXE so you can scan for filesystem problems if need be, and MSD.EXE (MicrosoftDiagnostics) so you can check your system setup, installeddisks, ports and channels.

Restore Software: If you are using backup software thatcomes with disaster recovery capabilities, the application

should create or allow you to create a floppy disk that containsthe program that will restore your system from backup. Makesure that you create this disk and include it as part of yourboot disk set.

Image Information: Image information created from yourhard disk file system should be stored on a floppy disk to allowyou to recover from disk problems.

Antivirus Software: Good antivirus products will include afloppy-disk-based version of their software, which will allow

you to boot and run the antivirus scanner directly from thefloppy disk. This is very useful since it will allow you to bypassany viruses on the hard disk. It isn't always possible to do thiswith all antivirus software, however, so you may have to bootfrom a clean floppy disk and then run the scanner from thehard disk (which should still work in most cases but isn't nearlyas good.)
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Editor: Many people don't think of this, but including a simpleeditor on the disk like DOS's EDIT.COM will allow you to makequick changes to configuration files if you need them, whichcan be a real life-saver.

Miscellaneous File Utilities: Any other file utilities you mayhave that you find useful should definitely be considered. Forexample, a simple file-transfer program can be helpful insetting up a new PC. I sometimes like to have DEFRAG.EXE ona boot disk, and MEM.EXE is helpful in diagnosing memoryusage on a new or just-upgraded system. PKUNZIP.EXE comesin handy for dealing with ZIP files, of course. And DOSKEY.COMis a helpful addition as well to any boot disk, as it will save youa lot of typing by letting you recall and reuse previously-typedcommands.

If you are using something like Norton Utilities or similar, a good antivirus product,and a backup program with disaster recovery, you may find that you will end up withseveral different emergency boot disks or "rescue disks". Again, there is nothingwrong with this at all, since floppies are pretty cheap. The only possible disadvantageis that you will spend more time keeping them all up to date.

Warning: One final word: if you are using a dynamic disk overlay product likeDisk Manager to allow you access to larger hard disks on a system without

proper native BIOS support, you must ensure that you have a boot disk that containsthe drive overlay software as well. Otherwise, if you boot using a regular boot disk,you will not be able to access your hard disk. This is very important! Usually the diskmanager program itself will come with a utility or menu item to create a boot disk thatincludes the overlay software.

Creating Boot Disks

Creating a boot disk is really a very simple affair, although it depends to some extenton what operating system you are using and what you want to put on the disk. Bear inmind that many utilities and backup applications will in fact create their own bootdisks for you. This can be a real time saver, although you often will find other thingsthat you want on your emergency disks that the software decided not to include. Seethis procedure for step-by-step instructions on creating boot disks.

Updating Boot Disks

Since the boot disks that you create as backup for your system contain keyinformation about your PC, you need to update them whenever your system changes.For most people, this is not very often. In fact, you probably only need to recreateyour boot disk on an annual basis, when you perform other maintenance tasks thatneed to be done once per year.
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In addition, you will want to update your boot disks immediately if you make majorchanges to your system, such as installing a new operating system. Not keeping your

boot disks up to date can leave you stranded at a time when you really need them.

Using Boot Disks

Using a boot disk is really very simple: you put the boot disk into whichever drive isthe boot device, and reset the PC. A cold reset via the reset button is preferred to using{Ctrl}+{Alt}+{Delete}, since the latter is just a software reset and will not clear thecontents of memory. You could of course cycle the power as well. Just rememberto shut down the system properly first before resetting.

When the PC reboots, it should load the operating system from the boot disk. SomePCs will not boot from floppy disks, however. This is usually because floppy disk

booting has been disabled via a BIOS setting. If this is the case, you will have to re-

enable floppy disk booting to use your disk.
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Documents

Backups and Disaster Recovery