Administrator's Guide

Auditing a Storage Pool Volume

Use this section to help you audit storage pool volumes for data integrity.

Task	Required Privilege Class
Audit volumes in storage pools over which they have authority	Restricted storage privilege
Audit a volume in any storage pool	System privilege, unrestricted storage privilege

The server database contains information about files on storage pool volumes. If there are inconsistencies between the information in the database about files and the files actually stored in a storage pool volume, users may be unable to access their files.

To ensure that all files are accessible on volumes in a storage pool, audit any volumes you suspect may have problems by using the AUDIT VOLUME command. You should audit a volume when:

• The volume is damaged

• The volume has not been accessed for a long period of time, for example, after six months

• A read or write error occurs while accessing the volume

• The database has been restored to an earlier point in time, and the volume is either a disk volume or a volume that was identified as being reused or deleted since the database backup took place

What Happens When You Audit Storage Pool Volumes

When you audit a volume, a background process is started. During the auditing process, the server:

• Records results of the audit in the activity log
• Sends informational messages about processing to the server console
• Prevents new files from being written to the volume

You can specify whether you want the server to correct the database if inconsistencies are detected. ADSM corrects the database by deleting database records that refer to files on the volume that cannot be accessed. The system default is to report inconsistencies that are found (files that cannot be accessed), but to not correct the errors.

If ADSM detects files with read errors, how ADSM handles these files depends on the following:

• The type of storage pool to which the volume is assigned
• The FIX option of the AUDIT VOLUME command
• The location of file copies (whether a copy of the file exists in a copy storage pool)

To display the results of a volume audit after it has completed, use the QUERY ACTLOG command. See "Requesting Information from the Activity Log".

Volumes in a Primary Storage Pool

For a volume in a primary storage pool, the values for the FIX parameter on an AUDIT VOLUME command have the following effects:

FIX=NO

ADSM reports, but does not delete, any database records that refer to files found with logical inconsistencies. If the AUDIT VOLUME command detects a read error in a file, ADSM marks the file as damaged in the database. You can do one of the following:

• If a backup copy of the file is stored in a copy storage pool, you can restore the file by using the RESTORE VOLUME or RESTORE STGPOOL command.

• If the file is a cached copy, you can delete references to the file on this volume by using the AUDIT VOLUME command again. Specify FIX=YES.

If the AUDIT VOLUME command does not detect a read error in a file that had previously been marked as damaged, the state of the file is reset so that the file can be used. For example, if a dirty tape head caused some files to be marked damaged, you can clean the head and then audit the volume to make the files accessible again.

FIX=YES

ADSM fixes any inconsistencies as they are detected.

If the AUDIT VOLUME command detects a read error in a file:

• If the file is not a cached copy and a backup copy is stored in a copy storage pool, ADSM marks the file as damaged in the database. The file can then be restored using the RESTORE VOLUME or RESTORE STGPOOL command.

• If the file is not a cached copy and a backup copy is not stored in a copy storage pool, ADSM deletes all database records that refer to the file.

• If the file is a cached copy, ADSM deletes the database records that refer to the cached file. The primary file is stored on another volume.

If the AUDIT VOLUME command does not detect a read error in a file that had previously been marked as damaged, ADSM resets the state of the file so that it can be used. For example, if a dirty tape head caused some files to be marked damaged, you can clean the head and then audit the volume to make the files accessible again.

Volumes in a Copy Storage Pool

For volumes in a copy storage pool, the values for the FIX parameter on an AUDIT VOLUME command have the following effects:

FIX=NO

ADSM reports the error and marks the file copy as damaged in the database.

FIX=YES

ADSM deletes references to the file on the audited volume from the database.

Auditing a Volume in a Disk Storage Pool

For example, to audit the /dev/vol1 disk volume and have only summary messages sent to the activity log and server console, enter:

audit volume /dev/vol1 quiet=yes

The audit volume process is run in the background and the server returns the following message:

+--------------------------------------------------------------------------------+
|ANR2313I Audit Volume NOFIX process started for volume /dev/vol1                |
|(process id 4).                                                                 |
+--------------------------------------------------------------------------------+

To view the status of the audit volume process, enter:

query process

The following figure displays an example of the audit volume process report.

+--------------------------------------------------------------------------------+
|                                                                                |
| Process Process Description      Status                                        |
|  Number                                                                        |
|-------- ------------------------ --------------------------------------------- |
|       4 Audit Volume             Storage Pool BACKUPPOOL, Volume               |
|         (Inspect Only)            /dev/vol1, Files Processed: 680,             |
|                                   Irretrievable Files Found: 0, Partial Files  |
|                                   Skipped: 0                                   |
+--------------------------------------------------------------------------------+

To display the results of a volume audit after it has completed, you can issue the QUERY ACTLOG command.

Auditing Multiple Volumes in a Sequential Access Storage Pool

When you audit a sequential storage volume containing files that span multiple volumes, the server selects all associated volumes. The server begins the audit process with the first volume on which the first file resides. For example, Figure 63 shows five volumes defined to ENGBACK2. In this example, File A spans VOL1 and VOL2, and File D spans VOL2, VOL3, VOL4, and VOL5.

Figure 63. Tape Volumes with Files A, B, C, D, and E

If you request that the server audit volume VOL3, the server first accesses volume VOL2, because File D begins at VOL2. When volume VOL2 is accessed, the server only audits File D. It does not audit the other files on this volume.

Because File D spans multiple volumes, the server accesses volumes VOL2, VOL3, VOL4, and VOL5 to ensure that there are no inconsistencies between the database and the storage pool volumes.

For volumes that require manual mount and dismount operations, the audit process can require significant manual intervention.

Auditing a Single Volume in a Sequential Access Storage Pool

To audit a single volume in a sequential storage pool, you can request that the server skip any files that span from the single volume to other volumes in the storage pool. This option is useful when the volume you want to audit contains part of a file, the rest of which resides on a different, damaged volume.

For example, to audit only volume VOL5 in the example in Figure 63 and have the server fix any inconsistencies found between the database and the storage volume, enter:

audit volume vol5 fix=yes skippartial=yes