Technical data

Managing Storage Media
9.13 Using Mount Verification for Recovery
Task Section
Control timeout periods for mount verification Section 9.13.2.2
Recover from offline errors Section 9.13.2.3
Recover from write-lock errors Section 9.13.2.4
Cancel mount verification using the DISMOUNT command Section 9.13.2.5
9.13.2.1 Enabling Mount Verification
Mount verification is enabled by default when you mount a disk or tape. To
disable mount verification, you must specify /NOMOUNT_VERIFICATION when
you mount a disk or tape.
Note that this feature applies to standard mounted tapes, foreign mounted tapes,
and Files-11 disks.
9.13.2.2 Controlling Timeout Periods for Mount Verification
You can control the amount of time (in seconds) that is allowed for a mount
verification to complete before it is automatically canceled. The MVTIMEOUT
system parameter for disks and the TAPE_MVTIMEOUT system parameter for
tapes define the time (in seconds) that is allowed for a pending mount verification
to complete before it is automatically canceled.
The default time limit for tapes is 600 seconds (10 minutes); for disks, it is 3600
seconds (1 hour). (Refer to the OpenVMS System Management Utilities Reference
Manual for more information about system parameters.)
Always set either parameter to a reasonable value for the typical operations at
your site. Note that resetting the value of the parameter does not affect a mount
verification that is currently in progress.
9.13.2.3 Recovering from Offline Errors
When a mounted disk or tape volume goes off line while mount verification is
enabled, you can try to recover, or you can terminate the mount request. The
following options are available:
• Try to put the device back on line by toggling the START or RUN button on
disks or the LOAD button on tapes. If the device has failed, terminate mount
verification.
• Take the disk or tape out of the offline and verification-pending state by
shutting down mount verification with one of the three techniques described
in Section 9.13.2.5. These techniques include canceling the mount request,
dismounting the volume, and allowing mount verification to time out.
If you successfully put the device back on line, the mount verification software
that polls the disk or tape drive begins verification in the following sequence of
steps:
1. The system checks to see that the currently mounted disk or tape has the
same identification as the previously mounted volume. In this way, mount
verification confirms that this is the same disk or tape that was previously
mounted and no switching has occurred.
If the drive contains the wrong volume, OPCOM issues a message in this
format:
Managing Storage Media 9–75