OpenVMS Undocumented Features
This is the most complete collection of undocumented features we can find for OpenVMS. Some of these have been around since the time when it was called VMS while others are more current and have been added to OpenVMS V8.n. These features:
- Are NOT documented (if they were, they wouldn't belong here)
- Are NOT supported by PARSEC Group or HP
- Are NOT guaranteed to work
- May NOT exist in all versions of OpenVMS; past, present and future
- Are subject to change, removal, enhancement or being documented at the whim of OpenVMS engineering
- May be fun to know the next time you play OpenVMS trivial pursuit
- May help you get your job done easier and faster
- May help you impress your boss with your knowledge of the obscure
Debug information from SHOW DEVICE command
Defining the SHOW$DEBUG logical name to 1 or TRUE causes the SHOW DEVICE command to display information about locks associated with the device. Defining the SHOW$DEBUG_LCKBUF logical name in addition to the SHOW$DEBUG logical name causes the raw data from the lock buffer to be dumped in ASCII and Hex format. The information may wrap for terminals with a width less than 132 columns.
$ define show$debug 1
$ define show$debug_lckbuf 1
$ show device sys$sysdevice
Locks queued to device lock "SYS$_$22$DKA300:":
- Lock 3A0000C6, length of items 00180078, $ENQ status 00000001, value block F8C7F9A1 00000000 00000000 00000019
- LOCKID PID SYSID (node) REMLKID REMSYSID RQMODE GRMODE STATE
- 6E000589 00000000 000100C4 (CLASS8) 02000180 000100CE (CLASS2) 01 01 01 [ CR / CR / GRANTED ]
- 19000C38 00000000 000100C4 (CLASS8) 13000123 000100CB (YIPPIE) 01 01 01 [ CR / CR / GRANTED ]
- 1900043D 00000000 000100C4 (CLASS8) 01000230 000100CA (CLASS9) 01 01 01 [ CR / CR / GRANTED ]
- 010000D7 00000000 000100C4 (CLASS8) 010000D7 000100C4 (CLASS8) 01 01 01 [ CR / CR / GRANTED ]
- 3A001103 39C003BD 000100C4 (CLASS8) 3A0000C6 000100CE (CLASS2) 00 00 01 [ NL / NL / GRANTED ]
- Formatted dump of LKI$_LOCKS buffer:
- 00000000 19000C38 000100CE 02000180 00010101 000100C4 00000000 6E000589 ...n....Ä...........Î...8....... 0000
- 00010101 000100C4 00000000 1900043D 000100CB 13000123 00010101 000100C4 Ä.......#...Ë...=.......Ä....... 0020
- 000100C4 010000D7 00010101 000100C4 00000000 010000D7 000100CA 01000230 0...Ê...×.......Ä.......×...Ä... 0040
- 00000000 00000000 000100CE 3A0000C6 00010000 000100C4 39C003BD 3A001103 ...:½.À9Ä.......Æ..:Î........... 0060
Device Device Error Volume Free Trans Mnt
Name Status Count Label Blocks Count Cnt
$22$DKA300: (CLASS2) Mounted 0 ALPHA83CLS 2018765 585 4
Setting process quotas for the Audit Server process
By defining any of the following logical names in executive mode before starting the Audit Server process, it is possible to set the related quotas for that process. If the Audit Server has already been started, then it must be stopped and restarted for the changes to take effect.
- AUDSRV$ASTLM - AST limit - default 200
- AUDSRV$BIOLM - Buffered I/O limit - default 200
- AUDSRV$BYTLM - Buffered I/O byte limit - default 100000
- AUDSRV$DIOLM - Direct I/O limit - default 200
- AUDSRV$ENQLM - ENQ limit - default 1000
- AUDSRV$PGFLQUOTA - Page file quota - default 20480
- AUDSRV$PRCLM - Process limit - default 10
- AUDSRV$WSDEFAULT - Working set default - default 150
- AUDSRV$WSQUOTA - Working set quota - default 250
- AUDSRV$WSEXTENT - Working set extent - default 2048
SHOW PATH command
The SHOW PATH /DEVICE command displays information about a specific path to multi-pathed devices. Adding the /FULL qualifier provides more detailed information, including the status of the last check of the path.
$ show device /multipath
Device Device Error Current
Name Status Count Paths path
$100$DKA0: (VMSPR1) Mounted 4 2/ 2 PKA0.0
$100$DKA1: (VMSPR1) Mounted 73 2/ 2 PKA0.0
$100$DKA4: (VMSPR1) Online 0 2/ 2 PKA0.0
$ show path/device pka0.0
Path Path Cur Tot Last Transition
Name Status Dev Cnt Dev Cnt of Availability
PKA0.0 Available 3 3 14-MAY-2007 07:17:24.35
$ show path/device pka0.0/full
Path: PKA0.0
Status1: 00000505 path_available,normal_timer,enabled_found,polling_started
Status2: 00000001 polling_enabled
Current UCB count: 3
Devices on path: 3
Time of last transition: 14-MAY-2007 07:17:24.35
Time user disabled: None
UCB used for polling: 81D2BDC0 (_$100$DKA0:)
poller TQE due time: 9-JUL-2007 08:57:24.47
Poller IRP iost1: 00000C7B Poller IRP iost2: 00000080
$ write sys$output f$message (%xc7b)
%SYSTEM-I-DEVCON, device is connected on path
Please enjoy these features at your own risk. If you are aware of other features in OpenVMS which are currently undocumented, you may use our inquiry form to inform us. We may then add it to our list.
