Index Management

Backup tracks the files it backs up in the client file indexes and the media database. The client file indexes keep track of the files that belong to a save set, and the media database tracks the name of the volume, the backup dates of the save sets on the volume, and the filesystems in each save set. Backup can automatically control the size of the client file indexes and media database according to the browse policies and retention policies you set. For more details about using browse and retention policies, see "How the Browse and Retention Policies Manage the Data Life Cycle ".

Index Size and Structure

The structure of the client file indexes avoids operating system restrictions on file size and allows the client file index for a single client to continue to grow. As the client file index grows, it splits into segments of 2 GB each. If you want to check the size of a client's file index, enter the nsrls -f command, for example:

# nsrls -f /nsr/index/clientname/db

The path in the example is the default path. To change the path where the index resides, change the value in the Index Path attribute in the details view of the Clients resource.

Do not use the UNIX ls command to check the size of the client's file index. The output of the nsrls -f command is a table, for example:

# nsrls -f /nsr/index/mars/db
Volume id 0: /nsr/index/mars/db
 Fid |    Kbytes |     Count | Name
------------------------------------------
   0 |     18504 |    119798 | sr
   1 |      2016 |    119798 | sr_i0
   2 |      1768 |    119436 | sr_i1

How to Manually Reduce the Client File Indexes and Media Database

You can also use manual methods to control the size of the client file indexes and the media database:

• Purge:

  # nsrmm -P volumename
  

  This method removes all relevant entries for user files on that volume from the appropriate client file indexes, but retains the volume in the media database. Purging a volume does not destroy the contents of the tape. You can still recover the contents using the scanner program.

• Delete:

  # nsrmm -d volumename
  

  This method removes the volume's entry from the media database. It also removes all the relevant entries for the user files on that volume from the client file index. Deleting a volume does not destroy the contents of the tape. You can still recover the contents using the scanner program.

• Recycle:

  # nsrmm -m -R volumename
  

  This method relabels the volume, deletes the volume from the media database, and reinitializes the tape. After a tape is recycled, you cannot use the scanner program to recover the contents.

When you purge or delete a volume, the client file indexes do not shrink automatically. Instead, the freed index space is used to allocate records that are added in the future. To reduce the size of the client file indexes immediately after you purge or delete index entries, run the following command:

# nsrck -C clientname

To reclaim the index space for all clients, change to the /nsr/index directory and run the nsrck -C command.

Large indexes may take up to a few hours to compress with nsrck. For more details, refer to the following man pages: nsrck, mminfo, scanner, nsr, nsrmm.

How to Override a Retention Policy

Save sets are retained on volumes and in the media database until the save sets expire. Ordinarily, a save set expires and is recyclable when the save set and all save sets that depend on it for recovery pass their retention policies. However, you can explicitly specify an expiration date for a save set that overrides the retention policy. Dependency rules still apply, however, which means that a save set is not marked "recyclable" until all save sets that depend on it are also marked as recyclable.

To explicitly override the retention policy, use the save -e manual backup command:

# save -e