Logical Disk Utility

The Logical Disk utility is a system management tool for controlling logical disk usage developed by Jur van der Burg based on the LD driver written by Adrie Sweep for VAX/VMS in 1985. LD has been a part of OpenVMS since VMS V7.3-1, fully integrated since Version 8.2.

Logical Disk

A logical disk is a file available on a physical disk, which acts as a real physical disk (the file may or may not be contiguous). The logical disks are available in any directory of the physical disk. Logical disks may be just a single disk, part of a volumeset, part of a stripeset, part of a host-based shadowset, part of a host-based raid set or any combination. The file to be used for the logical disk may be placed on any physical disk, in any directory. A backup can be made to protect the disk. A physical device may be 'replaced' by a logical disk to enable logging of all I/O of the physical disk.

Setup

To start using LD, you need to run LD$STARTUP.COM which is normally placed in SYS$STARTUP.

Commands

LD CREATE [/LOG] [/SIZE=xxx] [/BACKUP] [/CONTIGUOUS] [/LBN=xxx]
               [/TRACKS=xxx] [/SECTORS=xxx] [/CYLINDERS=xxx] [/ERASE]
               [/MAXBLOCKS=xxx] [/CLONE=device] [/EXTEND] Filespec

creates a file to be used as a logical disk

LD CONNECT [/LOG] [/SYMBOL] [/REPLACE] [/SHARE] [/CLONE=device]
               [/TRACKS=xxx] [/SECTORS=xxx] [/CYLINDERS=xxx] [/FULL]
               [/MAXBLOCKS=xxx] [/ALLOCLASS=xxx] [/AUTOGEOMETRY]
               [/OVERRIDE] [/SAVE] [/LBN=(START=xxx,END=xxx,COUNT=xxx)] 
               [/LOGICAL=(NAME=logical-name[,TABLE=table][,MODE=mode])]             
               [/LOCK] [/FORCED_ERROR] [/INIT] [/[NO]LOAD] [/EXTEND[=n]]
               [/LIMIT=n] Filespec [LDan:] [Logicalname]

connects the logical disk file to the logical disk device

LD LOAD Filespec LDan: (Qualifiers like CONNECT)

loads the specified file on the LM device

LD SWITCH Filespec LDan: (Qualifiers like CONNECT)

allows volume switching for backup. The existing virtual tapeunit is re-used with a the new container file. The old file will be disconnected.

LD DISCONNECT [/ALL] [/LOG] [/ABORT] [/TRUNCATE] LDan:

disconnects the logical disk device from the logical disk file, or from the physical disk

LD UNLOAD [/LOG] [/TRUNCATE] LDan:

unloads the specified file from the LM device. This is different from LM DISCONNECT in that the unit will be kept available for subsequent reuse with the LM LOAD command.

LD TRACE [/ACCURATE] [/FDT] [/SIZE=xxx] [/RESET] [/ALL] LDan:

initializes the trace buffer for the specified device

LD TRACE/STOP [/ALL] [LDan:]

stops another process which has issued a SHOW/TRACE/CONTINUOUS command

LD NOTRACE LDan:

deallocates the tracebuffer. All data currently available in the buffer will be lost

LD WATCH LDan: lbn [,lbn...] [/FUNCTION=READ,WRITE,ALL,CODE=xxx]
                   [/ACTION=SUSPEND,CRASH,OPCOM,ERROR[=xxx]]
                   [/FILE=filespec]

set a watchpoint on a virtual or logical blocknumber on the specified device

LD NOWATCH LDan: [lbn [,lbn...]] [/INDEX=n]

removes the specified watchpoint

LD WATCH/RESUME LDan: [lbn [,lbn...]] [/INDEX=n]

resumes a suspended watchpoint

LD PROTECT [/PERMANENT] LDan:

write-protects the specified device

LD NOPROTECT [/PERMANENT] LDan:

removes write-protection of the specified device

LD SHOW [/ALL] [/FULL] [LDan:]

Example:

$ ld show $34$LDA93:
%LD-I-CONNECTED, Connected $34$LDA93: to DISK:[JDOE]DKA200_USERDISK.DSK;2

$ ld show $34$LDA93: /full
%LD-I-CONNECTED, Connected $34$LDA93: to DISK:[JDOE]DKA200_USERDISK.DSK;2
-LD-I-OPTIONS, Not Forced Error capable

displays information about the status and the connected Logical Disk file or device

LD SHOW/WATCH LDan: [lbn [,lbn...]]

When this qualifier is specified, the currently set watchpoints of the specified device will be dumped.

LD SHOW/TRACE [/STATUS] [/RESET] [/OUTPUT=Filespec] [/INPUT=filespec]
              [/BINARY] [/ENTRIES=[(XXX,YYY)]] [/HEADER] [/CONTINUOUS]
              [/VERSION_LIMIT=xxx] [/BLOCKS=xxx] [/WARNINGS]
              [/NUMBER] [/PID] [/LBN] [/BYTECOUNT]
              [/IOSB[=COMBINATION,TEXT,HEX,LONGHEX]]
              [/TIMESTAMP[=ABSOLUTE,ELAPSED,COMBINATION,DELTA,START,END]]
              [/FUNCTION[=TEXT,HEX]] [/ACCURATE] [/FDT] [/SYMBOL] LDan:

When this qualifier is specified, the trace buffer of the specified device will be dumped

LD ANALYZE [/RECORDS[=HEX,DECIMAL]] [/DATA] [/DIRECTORY[=HEX,DECIMAL]]
               [/CONTINUE] [/OUTPUT=Filespec] Filespec

This command will verify the integrity of the container file. It can only be used for virtual tapes, disks have their own format (ODS-2/5).

LD HELP [command]

Displays help for the lodical disk utility and driver

LD VERSION

This command will show the current version of the LD utility and the driver.

See also

• Official website for LD driver info and updates
• Disk Partitioning on VMS:LD driver secrets (Jur van der Burg for OpenVMS Technical Journal V5, Jun 2005)