Vxvm Interview Questions

vxvm interview questions

1. How do you replace a failed boot disk under meta in solaris? Step by step explanation?

2. How do you remove meta only for the root slice? remaining slices should run under meta?

3. what you would do if you want to replace a slice using metareplace option?

4. what is the significance of 51% state database replicas in SVM?

5. what are the common errors you find in Solaris Volume manager?

6. You have a boot disk under svm, the machine fails to boot and remains in ok prompt? what could be the possible reason?

7. metastat -p shows a metavolume needs replacement. Metavolume is a single way mirror only. Actually you find disk and metavolumes are ok and I/O is happening to the filesystems… how will you remove the metareplace message that comes out of metastat.

8. How to create a shared disk group in VxVM?

9. What is the difference between private and public regions in Veritas Volume manager?

10. what would you do if the private region of a particular disk group is full? What are the design considerations for the size of private region in Vxvm disk group?

11. How to replace a corrupt private region? in vxvm 3.5 and greater versions…

12. How would you convert a volume from gen to fsgen? why should you do that?

13. How can you unencapsulate a boot disk in VxVM?

14. How to identify multiple paths for a disk.

15. What is the difference between Vxdmp and EMC powerpath?

16. vxdisk -o alldgs list o/p shows some disk groups in braces… What does that signify?

17. what are the various layouts that are available in VxVM?

18.What is a layered volume? how to create it using vxmake?

19.How to quickly mirror a volume, if the volume is empty?

20. How to grow a volume?

21. What is the difference between failing and failed disks?

22. How to replace a failed disk in Veritas?

23. Plex is in a disabled state. How will you recover? what are the steps to follow?

24.what is the difference between detached and disassociate state of plexes?

25. Whats the boot process of VxVM?

26. Whats the difference between SVM and VxVM? What would you recommend to your clients? why?

27.What are the various clusters you have worked on?

28. Which cluster is better VCS or Sun cluster?

29. Compare and contrast VCS and Sun Cluster.

30.how will you start VCS service? What are the configuration files in VCS?

31. How would switch a service group?

32. How would you freeze a service group?

33. What is a Split brain scenario ?

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# Name the mandatory disk group in VxVM 3.5 ? How will you configure VxVM in 3.5 ?

ANS: rootdg is the mandatory disk group in VxVM 3.5, vxinstall is the command to configure VxVM, It will create the disk groups, initializes the disks and adds them to the group.

# How will you create private and shared disk group using VxVM ?

ANS: For Private DG:

Command: vxdg init

For Shared DG:

Command: vxdg -s init < disk1 disk2 disk3 >

# Which are the different layouts for volumes in VxVM ?

ANS: mirror, stripe, concat (default one), raid5, stripe-mirror, mirror-stripe.

# What is the basic difference between private disk group and shared disk group ?

ANS: Private DG: The DG which is only visible for the host on which you have created it, if the host is a part of cluster, the private DG will not be visible to the other cluster nodes.

Shared DG: The DG which is sharable and visible to the other cluster nodes.

# How will you add new disk to the existing disk group ?

ANS: Run vxdiskadm command, which will open menu driven program to do various disk operations, select add disks option or you can use another command vxdiskadd.

# How will you grow/shrink the volume/file system ? What is the meaning of growby and growto options ? What is the meaning on shrinkto and shrinkby options ?

ANS: vxassist command is used to do all volume administration, following is the description and syntax.

Growby option: This is will grow your file system by adding new size to the existing file system.

Growto option: This will grow your file system as per the new size. This WILL NOT ADD new size to the existing one.

Shrinkby option: This will shrink your file system by reducing new size from existing file system.

Shrinkto option: This will shrink your file system as per the new size. This WILL NOT REDUCE the file system by reducing new size.

Command:

vxassist -g [growto, growby, shrinkto, shrinkby] length

# How will you setup and unsetup disks explicitly using VxVM ?

ANS: You can use /etc/vx/bin/vxdiskunsetup to unsetup the disk, and /etc/vx/vxdisksetup to setup the disk.

# How will you list the disks, which are in different disk groups ?

ANS: vxdisk list is the command will list the disks from the DG which is currently imported, you can check the same using vxprint command too. vxdisk -o alldgs list command list all the disks which are in different dg's.

# What is the private region in VxVM ?

ANS: Private region stores the structured VxVM information, it also stores the disk ID and disk geometry. In short words it has metadata of the disk.

# If, vxdisk list command gives you disks status as "error", what steps you will follow to make the respective disks online ?

ANS: If you faced this issue because of fabric disconnection then simply do vxdisk scandisks, otherwise unsetup the disk using using /etc/vx/bin/vxdiskunsetup and setup the disks again using /etc/vx/bin/vxdisksetup, this will definitely help! [ /etc/vx/bin/vxdiskunsetup will remove the private region from the disk and destroys data, backup the data before using this option]

what is the significance of 51% state database replicas in SVM?

if the system is having 51 % of replica the system will boot

up normally, but if there are less then or = 50% of replicas

are present in the system , then the system will panic. In

this situation boot the system into single user mode and

delete the unavailable replica and create new set of

replicas and boot the system.

what are the common errors you find in Solaris Volume manager?

Disk c#t#d# is faulty and need to be replaced

Question What is a layered volume? how to create it using vxmake?

Answer

# 1 stripe- mirror

concat - mirror are layered volumes and

## First make subdisks

vxmake -g sybdg sd sybdg32-15 sybdg32,14607200,1365376





vxmake -g sybdg sd sybdg56-30 sybdg56,27216512,1365376##

Now make the plexes

vxmake -g sybdg plex datadev93-SV00A sd=sybdg32-15



vxmake -g sybdg plex datadev93-SV00B sd=sybdg54-17



## Now create sub volumes containing the plexes.

vxmake -g sybdg vol datadev93-SV00 plex=datadev93-

SV00A,datadev93-SV00B use_type=gen


SV01A,datadev93-SV01B use_type=gen


SV02A,datadev93-SV02B use_type=gen##

Let them be subvolumes

vxedit -g sybdg set layered=on datadev93-SV00 datadev93-

SV01 datadev93-SV02

## Activate!

vxvol -g sybdg init active datadev93-SV00



## Turn into subdisks so we can add them all to another plex

vxmake -g sybdg sd datadev93-SD00 datadev93-SV00,0,1365376



## Now create a new plex with all subvolumes in

vxmake -g sybdg plex datadev93-A sd=datadev93-

SD00,datadev93-SD01,datadev93-SD02 layout=stripe

st_width=128

## Now make the main volume

vxmake -g sybdg vol datadev93 plex=datadev93-A

use_type=genvxvol -g sybdg init active datadev93

#vxedit -g sybdg set user=sybase group=dba datadev93

Veritas File System fixed issues

The following table contains information about fixed issues in this release of VxFS.

Incident

Description

472089

vxfs_ninode and vx_bc_bufhwm tunables are now dynamic.

478142

fsck binaries are included for older log versions.

511750

Swap space and tunable changes were required for using fsck and mkfs on big file systems.

Veritas Volume Manager fixed issues

The following table contains information about fixed issues in this release of VxVM.

Incident

Description

137175

The vxdiskadm utility no longer truncates default disk names to 9 characters.

140947

I/O policy settings were not persistent between reboots.

229538

Multiple enclosures of the same type generated unexpected enclosure-based names.

272263

Changing a disk's I/O policy could hang vxconfigd.

272309

Incomplete records in /etc/vx/disk.info could cause vxconfigd to dump core.

272891

vxnotify did not receive events relating to the change of controller states in DMP.

311530

Renaming an enclosure with a longer name caused vxconfigd to dump core.

506139

If the naming scheme was changed, the default arguments to vxconfigd were not preserved.

Recover/Start a volume that has a plex in the disabled & recover state

January 6, 2008 by sun4u

The vxprint -ht output gives, among other things, the kernel state (column 4) and the state (column 5) of a plex .

Consider the following case:

# vxprint -ht -g testdg

DG NAME NCONFIG NLOG MINORS GROUP-ID

DM NAME DEVICE TYPE PRIVLEN PUBLEN STATE

RV NAME RLINK_CNT KSTATE STATE PRIMARY DATAVOLS SRL

RL NAME RVG KSTATE STATE REM_HOST REM_DG REM_RLNK

V NAME RVG KSTATE STATE LENGTH USETYPE PREFPLEX RDPOL

PL NAME VOLUME KSTATE STATE LENGTH LAYOUT NCOL/WID MODE

SD NAME PLEX DISK DISKOFFS LENGTH [COL/]OFF DEVICE MODE

SV NAME PLEX VOLNAME NVOLLAYR LENGTH [COL/]OFF AM/NM MODE

dg testdg default default 84000 970356463.1203.alu

dm testdg01 c1t4d0s2 sliced 2179 8920560 -


v test – DISABLED ACTIVE 17840128 fsgen – SELECT

pl test-01 test DISABLED RECOVER 17841120 CONCAT – RW

sd testdg01-01 test-01 testdg01 0 8920560 0 c1t4d0 ENA


From the above output, it can be seen that the volume test has plex test-01 in the DISABLED and RECOVER state.

To recover the volume test, use the vxmend command. This operation applies only to volumes, or to plexes associated with a volume. This will manually reset or change the state of a plex or volume.

The following is the procedure to recover/start this volume:

1. Bring plex test-01 to the DISABLED and OFFLINE state using the following command: vxmend -o force off <recover_plex>

For example,

# vxmend -o force off test-01

The below output shows plex test-01 in the DISABLED and OFFLINE state:














pl test-01 test DISABLED OFFLINE 17841120 CONCAT – RW



2. Bring plex test-01 to the DISABLED and STALE state using the following command: vxmend on <recover_plex>

For example,

# vxmend on test-01

The below output shows plex test-01 in the DISABLED and STALE state:














pl test-01 test DISABLED STALE 17841120 CONCAT – RW



3. Bring plex test-01 to the DISABLED and CLEAN state using the following command: vxmend fix clean <recover_plex>

For example,

# vxmend fix clean test-01

The below output shows plex test-01 in the DISABLED and CLEAN state:














pl test-01 test DISABLED CLEAN 17841120 CONCAT – RW



4. Once plex test-01 is in the DISABLED/CLEAN state, the volume test can be started with the following command: vxvol start <volume>

For example,

# vxvol start test

It can be seen in the below output that the volume is now ENABLED and ACTIVE:













v test – ENABLED ACTIVE 17840128 fsgen – SELECT

pl test-01 test ENABLED ACTIVE 17841120 CONCAT – RW



Question what is the difference between detached and disassociate

state of plexes?

Answer

# 2 when you detach the plex from volume means i/o performance

will stop from detached plex

we can understand that we took the backup of the plex we can

attach this plex any time to any volume

Disassociate plex means we are breaking the link between

volume and plex we can can't attach this plex to any volume

but if server reboot plex will be sync with volume

Question Whats the boot process of VxVM?

Boot Process of vxvm is as similar as solaris booting but

the only difference is when we bring the root disk under

vxvm control there is one entrie will be created

under /etc/system file starts with "rootdev" This will read

by the kernel before loading the modules and it helps

system to mount root volume rather than root partition.

Question Whats the difference between SVM and VxVM? What would you

recommend to your clients? why?

Answer

# 1 SVM:

1. Inbuild in Solaris.

2. Only available for Solaris

3. Can't decrease online the volume size.

VxVM:

2. Third party tool.

2. Available for all popular OS (Solaris,Linux,Windows,HP-

UX,AIX etc.)

3. Can resize (increase or decrease) the volume online.

Question how will you start VCS service? What are the configuration

files in VCS?

Answer

# 2 hastart

/etc/VRTSvcs/conf/config/main.cf

/etc/llttab

/etc/llthosts

/etc/gabtab

/etc/VRTSvcs/conf/config/types.cf

Question How would switch a service group?

Answer

# 2 (1) hagrp -switch {Service Group} -to {target node}

(2) hagrp -offline {Service Group} -sys {current node}

(3) hagrp -online {Service Group} -sys {target node}

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Vxvm Interview Questions