© 2006 Hewlett-Packard Development Company, L.P.The information contained herein is subject to change without notice

Disk partitioning on VMS with LDdriver

Session A311/A312

Jur van der BurgHP OpenVMS Engineering

April 21, 2023 2

LDdriver: What can it do?

• Use a file on any disk as a disk• Use a range of logical blocks on a disk as a

new disk• Investigate I/O behavior• Test application error handling• Play around with disks without doing

damage• Emulate a magtape (future)• Create havoc (with privileges)

April 21, 2023 3

Where can I find it?• On the OpenVMS freeware website

http://www.hp.com/go/openvms/freeware

• On the main lddriver site http://www.digiater.nl/lddriver (under construction)

• Integrated in VMS since V7.3-1(sort of....)• Fully integrated in VMS V8.2

April 21, 2023 4

Preparation• Ready for use after

@SYS$STARTUP:LD$STARTUP• Any command that needs the driver will

give an error if not started properly:$ LD CONNECT FILE.DSK LDA1

%LD-F-INVOKESTARTUP, LD has not been setup correctly, invoke @SYS$STARTUP:LD$STARTUP.COM

• Exceptions are LD HELP and LD CREATE• Version can be obtained like this:

$ LD VERSION%LD-I-VERSION, LD version V9.0, module X-9 built on May 17 2006 09:01:31-LD-I-DRIVERVERSION, Driver version: 17-MAY-2006 09:02:10.86 (MON version)-LD-I-SYSINFO, Node: THEBAT, Hardware: hp AlphaServer DS20L 833 MHz, VMS version: XB9P-BL2

April 21, 2023 5

Basics – File mode• Use a file as a disk• Create a file on a physical disk:

LD CREATE DKA100:[LD]DISK/SIZE=10000

• Connect the file to a device:LD CONNECT DKA100:[LD]DISK LDA1

• Use it:INIT LDA1: LDDISKMOUNT LDA1: LDDISK.....DISMOUNT LDA1:

• Disconnect the file:LD DISCONNECT LDA1

April 21, 2023 6

Basics – LBN mode• Use a range of logical blocks as a disk• Physical disk may not be used by anything

else • Connect a range of logical blocks to a disk:

LD CONNECT DKA100:/LBN=(START=0,END=9999) LDA1LD CONNECT DKA100:/LBN=(START=10000,END=19999) LDA2LD CONNECT DKA100:/LBN=(START=20000,END=29999) LDA3

• Connect using a size:LD CONNECT DKA100:/LBN=(START=0,SIZE=10000) LDA1LD CONNECT DKA100:/LBN=(START=10000,SIZE=10000) LDA2LD CONNECT DKA100:/LBN=(START=20000,SIZE=10000) LDA3

April 21, 2023 7

Basics – Replace mode• Access another disk via an LD device• Not a real form of partitioning• Useful for I/O tracing and watchpoints• Physical disk may not be used by anything

else• Connect and replace:

LD CONNECT DKA100:/REPLACE LDA1

April 21, 2023 8

Advanced use• Sharing of LD devices in a cluster is

possible• LD devices itself are not MSCP-served• For shared use the physical devices where

the container file resides must be MSCP served

• Shadowing host-based raid disks• LD devices may be nested, i.e. you can

create an LD disk on an LD disk on an LD disk etc.

April 21, 2023 9

Sharing LD devices• LD devices must be connected the same

way on multiple nodes to allow sharing of container files

• This means the same device name, allocation class, geometry, filename, etc.

• Any mismatch will be detected by the driver

• The utility attempts to give the reason for the failure$ ld connect $1$dga1: lda3:/lbn=(start=600,end=2000)/log/share%LD-F-DEVICEINUSE, Device incompatible connected to other LD disk in

cluster-LD-F-RANGEINUSE, LBN range already in use

April 21, 2023 10

I/O tracing• Very powerful feature to see what’s

happening on a low level• Can be viewed real-time (continuously)• Can be logged to disk (unattended)• Flexible selectable output−different time formats−different I/O status block formats−different I/O function code formats

April 21, 2023 11

I/O Tracing example$ ld trace lda1:.....$ ld show/trace lda1

I/O trace for device $7$LDA1: 26-APR-2006 22:18:36.28 on node LDDRVR::Start Time Elaps Pid Lbn Bytes Iosb Function--------------------------------------------------------------22:18:32.65 00.00 09C00227 0 0 NORMAL PACKACK|INHERLOG22:18:32.65 00.01 09C00227 1 512 NORMAL READPBLK22:18:32.66 00.00 09C00227 1034 512 NORMAL READPBLK22:18:32.67 00.00 09C00227 5002 512 NORMAL READPBLK22:18:32.68 00.00 09C00227 5002 512 NORMAL WRITEPBLK22:18:32.69 00.00 09C00227 5003 1536 NORMAL READPBLK22:18:32.69 00.00 09C00227 5006 512 NORMAL READPBLK22:18:32.69 00.00 09C00227 5000 512 NORMAL READPBLK|EXFUNC22:18:32.69 00.00 09C00227 0 0 NORMAL PACKACK|BYPASS_VALID_CHK22:18:32.70 00.00 09C00227 5016 512 NORMAL READPBLK|EXFUNC22:18:32.70 00.00 09C00227 5023 1024 NORMAL READPBLK22:18:32.70 00.00 09C00227 5016 512 NORMAL WRITEPBLK|EXFUNC|DATACHECK

April 21, 2023 12

Watchpoints• A watchpoint is a special action performed when

a targeted logical block is hit by a request• These actions are possible:−Return a specific error−Suspend the I/O request−Generate an Opcom message−Crash the system (needs CMKRNL privilege)

• The user controls which LBN is watched, on which function code is acted, and which error is returned

• The ‘Opcom’ action may be combined with other actions

April 21, 2023 13

Watchpoint example$ ld watch lda1 1/action=error=2928$ ld watch lda1 1/action=opcom$ ld show/watch lda1Index LBN Action Function Error return code-------------------------------------------------------------------- 1 1 Opcom READPBLK 2 1 Error READPBLK 0B70 (FISH)

$ dump lda1:/block=(count=1,start=1)%%%%%%%%%%% OPCOM 5-APR-2006 14:21:46.70 %%%%%%%%%%%Message from user VDBURG on LDDRVR***** LDdriver detected LBN watchpoint access *****PID: 26000224Image: DUMPDevice: $7$LDA1: (LDDRVR)Function: 000CLBN: 1

%DUMP-E-READERR, error reading LDA1:-SYSTEM-W-FISH, my hovercraft is full of eels

April 21, 2023 14

Callable interface• LDdriver is controlled by a user mode

program issuing normal QIO requests• The required function codes and definitions

are available in the kit, and in VMS since V8.2-1 ($LDDEF or lddef.h)

• The driver is doing very strong validity checks of all requests (You can’t shoot yourself in the foot (if you can, I apologize, please let me know how you did it))

April 21, 2023 15

Limits• Create as many devices as your diskspace

allows• Creation of any device takes BYTLM quota

from the creating process• The tracebuffer as well as watchpoints

come out of non-paged pool and are charged against BYTLM as well

• If 9999 LD devices are not enough then you can create LD devices on other controllers, like LDB1:, LDC1:, etc.

• Configure the driver with @SYS$STARTUP:LD$STARTUP x where x is the controller to use.

April 21, 2023 16

New developments• LD V8.1:

−LD CREATE/EXTENDAllows extension of existing container fileExpand volume with SET VOLUME/SIZE

−LD CONNECT/NOFORCED_ERRORPrevent handling of forced errors with shadowing

−Bug fixes:• Fix possible system crash in I/O completion• Fix I/O hang with host-based raid• Fix mount verification issues

April 21, 2023 17

New developments• LD V8.2:

−LD V8.2 has no new features when compared to V8.1

− It is only a bug fix release.• Properly expel shadowset members on error• Reconnecting an LD device could fail the first time after

reboot if the container file was used on another node• Allow container file on an NFS mounted ODS5 volume• Prevent system crash on reconnecting a container file

in a cluster

April 21, 2023 18

New developments - cont• LD V9.0:

− LD CREATE/ERASEErase container file on creation

− More accurate timing in trace records (starting with VMS V8.3)

$ ld show/trace lda1 I/O trace for device $9$LDA1: 17-MAY-2006 09:21:15.16 on node THEBAT

End Time Elaps Pid Lbn Bytes Iosb Function---------------------------------------------------------------------09:21:12.232269 00.000000 2060042F 0 0 NORMAL PACKACK|INHERLOG09:21:12.240950 00.008581 2060042F 1 512 NORMAL READPBLK09:21:12.247513 00.006426 2060042F 1034 512 NORMAL READPBLK09:21:12.248595 00.000959 2060042F 50033 512 NORMAL READPBLK09:21:12.249557 00.000838 2060042F 50034 512 NORMAL READPBLK09:21:12.255176 00.005504 2060042F 50016 512 NORMAL READPBLK09:21:12.263548 00.008258 2060042F 50016 512 NORMAL WRITEPBLK

April 21, 2023 19

New developments – Tape emulation• Emulate tape device (not yet finished)−Device is called ‘LM’ (Logical Magtape)−Uses the same driver as LD

$ lm create tape1/siz=10000$ lm connect tape1 lma1/log%LD-I-CONNECTED, Connected $9$LMA1: to $9$DKA100:[LD]TAPE1.DSK;1$ show dev/fu lma1

Magtape $9$LMA1: (THEBAT), device type (Generic SCSI tape), is online, file- oriented device.

Error count 0 Operations completed 2 Owner process "" Owner UIC [JUR] Owner process ID 00000000 Dev Prot S:RWPL,O:RWPL,G:R,W Reference count 0 Default buffer size 2048 Density 6666 Format Normal-11 Allocation class 12

Volume status: no-unload on dismount, odd parity.

April 21, 2023 20

New developments – Tape emulation

$ lm trace lma1$ mount/for lma1:%MOUNT-I-MOUNTED, mounted on _$9$LMA1: (THEBAT)$ dismount lma1:$ lm show/trace lma1 I/O trace for device $9$LMA1: 17-MAY-2006 09:25:49.65 on node THEBAT

End Time Elaps Pid Lbn Bytes Iosb Function---------------------------------------------------------------------09:24:12.914151 00.000000 000000A9 0 0 NORMAL PACKACK09:24:12.914153 00.000000 000000A9 0 0 NORMAL REWIND09:24:12.914157 00.000000 000000A9 0 0 NORMAL PACKACK09:24:12.914159 00.000000 000000A9 0 0 NORMAL REWIND09:24:12.914161 00.000000 000000A9 0 80 ILLBLKNUM READPBLK09:24:12.914163 00.000000 000000A9 0 0 NORMAL REWIND09:24:12.980426 00.000000 000000A9 0 0 NORMAL UNLOAD|CLSEREXCP09:24:12.980427 00.000000 000000A9 0 0 NORMAL AVAILABLE

April 21, 2023 21

Internals – connecting a container file• The most tricky part is connecting an LD

device to a container file−Container file physical device must be a

mounted disk− It must contain a known file system−File must be mapped with cathedral windows−Caching must be disabled for this file−Check for usage on other cluster members

• File ID• Allocation class• Device name / controller letter / unit number• Geometry• Maximum block size• Sharing• Mode of connection

April 21, 2023 22

Internals – connecting a disk by LBN• Connecting part of a disk by LBN range

needs other checks−Physical device may not be mounted− It may not be accessed on any other node−The logical block range must fit and may not be

in use anywhere in the cluster−The exception is that parts that match exactly

may be shared−After connecting the physical device is guarded

against access with a lock which prevents mounting

April 21, 2023 23

Internals – checking LBN range (1)• When connecting a part of a physical disk

we need to check availability of the logical blocks, clusterwide−We can’s take out a lock based on a resource

name with the encoded range as we don’t know what’s used on other nodes−We don’t want to invoke a helper process –

driver check only!−We can’t store all ranges in a valueblock−So we use the lockmanager in a smart way

April 21, 2023 24

Internals – checking LBN range (2)• At connection time the block range we

want is entered in a lock value block• By taking out a lock a blocking AST routine

is fired on other nodes with interest in the same device−The blocking routine scans all local LD devices

for a matching device− If found the LBN range is checked− In case of an error a bit is set in the lock value

block−After lock conversion the initiator examines the

error bit and rejects the request if set

April 21, 2023 25

Internals – Finding an I/O• LDdriver sends most I/O requests it

receives directly to the physical disk driver• This may happen for multiple file segments

in parallel• This can make it harder to find an active I/O− IRP’s forwarded to the physical disk can be

found in the LDIOB structure−LDdriver’s structure definitions can be found in

SYS$LDDRIVER.STB (only after installing the LD kit)

April 21, 2023 26

SDA> read/execSDA> show device lda2...SDA> format/typ=ldiob @(ucb+ucb$l_ld_aiofl)FFFFFFFF.81DDE140 LDIOB$L_QFL 81DD9800 UCB+00200FFFFFFFF.81DDE144 LDIOB$L_QBL 81DD9800 UCB+00200FFFFFFFF.81DDE148 LDIOB$W_SIZE 0080FFFFFFFF.81DDE14A LDIOB$B_TYPE 13FFFFFFFF.81DDE14B LDIOB$B_SPARE 53FFFFFFFF.81DDE14C LDIOB$L_IRP 81DB1780FFFFFFFF.81DDE150 LDIOB$L_PID 0001002B LNM$C_DEL_OVERLAY+00027FFFFFFFF.81DDE154 LDIOB$L_MEDIA 00000000FFFFFFFF.81DDE158 LDIOB$L_BCNT 00000200FFFFFFFF.81DDE15C LDIOB$W_FUNC 000CFFFFFFFF.81DDE15E LDIOB$W_IOST 0001FFFFFFFF.81DDE160 LDIOB$Q_STAT 00000000.00000000FFFFFFFF.81DDE168 LDIOB$Q_ST_TIME 00000000.00000000FFFFFFFF.81DDE170 LDIOB$Q_EN_TIME 000000A8.00010025FFFFFFFF.81DDE178 LDIOB$Q_ST_SCC 00000000.1C10E15DFFFFFFFF.81DDE180 LDIOB$Q_EN_SCC 44070017.34465003FFFFFFFF.81DDE188 LDIOB$L_ST_CPU 00000000FFFFFFFF.81DDE18C LDIOB$L_EN_CPU 00000000FFFFFFFF.81DDE190 LDIOB$L_ELAPSED 00000000 LDIOB$Q_ELAPSEDFFFFFFFF.81DDE194 00000000FFFFFFFF.81DDE198 LDIOB$Q_ST_USEC 613D6500.746C7561FFFFFFFF.81DDE1A0 LDIOB$Q_EN_USEC 2F657461.642F6C6CFFFFFFFF.81DDE1A8 LDIOB$L_ABCNT 00000000 Number of bytes transferred so farFFFFFFFF.81DDE1AC LDIOB$L_KPB 81C5C9C0FFFFFFFF.81DDE1B0 LDIOB$L_FWDQFL 81DC0878 Queue of forwared IRP'sFFFFFFFF.81DDE1B4 LDIOB$L_FWDQBL 81DC0878FFFFFFFF.81DDE1B8 LDIOB$W_IRPCNT 0001 Number of active forwarded IRP'sFFFFFFFF.81DDE1BA LDIOB$W_FLAGS 0000SDA> format @(@(ucb+ucb$l_ld_aiofl)+ldiob$l_fwdqfl)-irp$l_ld_fwdqflFFFFFFFF.81DC0640 IRP$L_IOQFL 81DC5BA0FFFFFFFF.81DC0644 IRP$L_IOQBL 81DC5BA0FFFFFFFF.81DC0648 IRP$W_SIZE 0240FFFFFFFF.81DC064A IRP$B_TYPE 0AFFFFFFFF.81DC064B IRP$B_RMOD 00FFFFFFFF.81DC064C IRP$L_PID 81B278F0 SYS$LDDRIVER+118F0...

April 21, 2023 27

Which VMS versions?• Runs on VAX/VMS since V5.5-2• Alpha V6.1 and higher• IA64 V8.2 and higher

• The current kit is HP-VMS-LD-V0802--1.PCSI• Installs on:• VAX V7.3• Alpha V7.2-2 V7.3 V7.3-1 V7.3-2 V8.2• Ia64 V8.2 V8.2-1

April 21, 2023 28

Other versions• Other versions may work too, but the driver

and utility needs to be built from source (included in the kit)

• Build procedure is included• C compiler required• Driver may need an edit for specific

versions (enable / disable a conditional)• LD V9.0 will NOT run on VAX!• LD V8.2 is integrated in the VMS V8.3

release

April 21, 2023 29

Known issues• V8.2:

− If the XFC cache is turned off (VCC_FLAGS != 2) then connecting a file will return this error:• %LD-F-BLKOUTOFRANGE, Blocks out of range

−This problem is corrected in VMS V8.3 and the future LD V9.0 kit

April 21, 2023 30

Internal usage• Heavily used for testing• Used in the VMS build• Used by the host-based Infoserver• Used by CDRECORD

April 21, 2023 31

Futures• Bug fixes (if any....)• You name it.... suggestions are welcome

(buy me a beer )

April 21, 2023 32

More information• LDDRIVER article in the HP technical journal

http://www.hp.com/go/openvms/journal

• After installation: $ LD HELP

• Questions / Bugs / Ideas?Email: lddriver@digiater.nl

April 21, 2023 34

LD_FILE.COM$ ld create disk1.dsk /size=5000$ ld connect disk1.dsk lda1:$ ld show lda1:$ ld trace lda1:$ init lda1: test$ mount lda1: test$ dir lda1:[000000]$ ld show/trace lda1:$ ld trace/reset lda1:$ dismount lda1:$ ld show/trace lda1:$ ld disconnect lda1:$ delete disk1.dsk;

April 21, 2023 35

LD_FILE_SHARE.COM$ if f$search("disk1.dsk") .eqs. ""$ then$ ld create disk1.dsk /size=5000$ ld connect disk1.dsk lda1:/share/alloclass=4/log$ init lda1: test$ else$ ld connect disk1.dsk lda1:/share/alloclass=4/log$ endif$ mount/system lda1: test$ show dev lda1$ inquire dummy "return to continue"$ dismount lda1:$ ld disconnect/log lda1:$ if f$search("disk1.dsk") .nes. "" then delete disk1.dsk;

April 21, 2023 36

LD_FILE_SHARE_LOCK.COM$ if f$search("disk1.dsk") .eqs. ""$ then$ ld create disk1.dsk /size=5000$ ld connect disk1.dsk lda1:/share/alloclass=4/log/lock$ init lda1: test$ else$ ld connect disk1.dsk lda1:/share/alloclass=4/log/lock$ endif$ mount/system lda1: test$ show dev lda1$ inquire dummy "return to continue"$ dismount lda1:$ ld disconnect/log lda1:$ if f$search("disk1.dsk") .nes. "" then delete disk1.dsk;

April 21, 2023 37

LD_FILE_TRACE.COM$ on control_y then goto exit$ ld create disk1.dsk /size=5000$ ld connect disk1.dsk lda1:/log$ init lda1: test$ mount lda1: test$ ld trace lda1:$loop:$ dir lda1:[000000]$ wait 0:0:5$ analyze/disk lda1:$ wait 0:0:5$ goto loop$ dismount lda1:$exit:$ set noon$ dismount lda1:$ ld trace/stop lda1:$ ld disconnect lda1:$ delete disk1.dsk;

April 21, 2023 38

LD_FILE_SHADOW.COM$ ld create disk1.dsk /size=5000$ ld create disk2.dsk /size=5000$ ld connect disk1.dsk lda1:/log/alloclass=4$ ld connect disk2.dsk lda2:/log/alloclass=4$ ld trace lda1:$ ld trace lda2:$ init lda1: test$ mount dsa0:/shadow=($4$lda1:,$4$lda2:) test$ ld show/trace lda1:$ ld show/trace lda2:$ ld trace/reset lda1:$ ld trace/reset lda2:$ show shadow/copy$ inquire dummy "return to continue"$ dismount dsa0:$ ld show/trace lda1:$ ld show/trace lda2:$ ld disconnect lda1:$ ld disconnect lda2:$ delete disk1.dsk;$ delete disk2.dsk;

April 21, 2023 39

LD_LBN.COM$ phdev := $9$dka400:$ show dev 'phdev'$ ld connect 'phdev' lda1:/log/lbn=(start=0,count=10000)$ ld connect 'phdev' lda2:/log/lbn=(start=10000,count=10000)$ ld connect 'phdev' lda3:/log/lbn=(start=20000,count=10000)$ ld connect 'phdev' lda4:/log/lbn=(start=30000,count=10000)$ init lda1: test1$ init lda2: test2$ init lda3: test3$ init lda4: test4$ mount lda1: test1$ mount lda2: test2$ mount lda3: test3$ mount lda4: test4$ show dev lda1$ show dev lda2$ show dev lda3$ show dev lda4$ show dev 'phdev'$ inquire dummy "return to continue"$ dismount lda1:$ dismount lda2:$ dismount lda3:$ dismount lda4:$ ld disconnect/log/all$ show dev 'phdev'

April 21, 2023 40

LD_LBN_SHARE.COM$ phdev := $9$dka400:$ show dev 'phdev'$ ld connect 'phdev' lda1:/log/lbn=(start=0,count=10000)/share/alloclass=4$ ld connect 'phdev' lda2:/log/lbn=(start=10000,count=10000)/share/alloclass=4$ ld connect 'phdev' lda3:/log/lbn=(start=20000,count=10000)/share/alloclass=4$ ld connect 'phdev' lda4:/log/lbn=(start=30000,count=10000)/share/alloclass=4$ mount/system lda1: test1$ mount/system lda2: test2$ mount/system lda3: test3$ mount/system lda4: test4$ show dev lda1$ show dev lda2$ show dev lda3$ show dev lda4$ show dev 'phdev'$ inquire dummy "return to continue"$ dismount lda1:$ dismount lda2:$ dismount lda3:$ dismount lda4:$ ld disconnect/log/all$ show dev 'phdev'

April 21, 2023 41

LD_REPLACE.COM$ phdev := $9$dka400:$ show dev 'phdev'$ ld connect 'phdev' lda1:/log/replace$ ld trace lda1:$ init lda1: test1$ mount lda1: test1$ show dev/full lda1$ show dev/full 'phdev'$ ld show/trace lda1:$ inquire dummy "return to continue"$ dismount lda1:$ ld disconnect/log lda1:$ show dev 'phdev'

April 21, 2023 42

LD_MOUNTVER.COM$ ld create disk1.dsk$ ld connect/log/symbol disk1.dsk$ init/nohigh/system lda'ld_unit': test$ mount lda'ld_unit': test$ ld trace lda'ld_unit':$ ld watch lda'ld_unit': 1/action=error=%x84/function=code=%x0808$ ld watch lda'ld_unit': 10/action=error=%x84/function=read$ ld watch lda'ld_unit': 10/action=opcom/function=read$ ld show/watch lda'ld_unit':$ reply/enable/temp$ spawn/nowait/input=nl: dump lda'ld_unit':/block=(start=10,count=1)$ inquire dummy "return to continue"$ ld nowatch lda'ld_unit':$ ld show/trace lda'ld_unit':$ reply/disable$ wait 0:0:1$ dism lda'ld_unit':$ set noon$ ld trace/stop lda'ld_unit':$ ld disc lda'ld_unit':$ delete/nolog/noconf disk1.dsk;