About frozen media
Frozen media is the media that NetBackup does not use for backups. NetBackup stops directing the backups and the archives to frozen media. NetBackup never deletes a frozen media ID from the NetBackup media catalog, even after the retention period ends for all backups on the media. NetBackup does not unassign a frozen volume from the NetBackup volume pool when its backup images expire.
All unexpired backup images on frozen media continue to be available for restores.
NetBackup freezes the tape volumes for a variety of reasons, as follows:
NetBackup freezes a volume when read or write errors surpass the threshold within the time window. The default media error threshold is 2. That is, NetBackup freezes media on the third media error in the default time window (12 hours).
Common reasons for write failures are dirty write heads or old media. The reason for the action is logged in the NetBackup error catalog (view the Media Logs report or the All Log Entries report).
You can use the NetBackup nbemmcmd command with the -media_error_threshold and -time_window options to change the default values.
For more information about the nbemmcmd command, see the NetBackup Commands Reference Guide.
NetBackup freezes a volume if a write failure makes future attempts at positioning the tape unreliable.
NetBackup freezes the catalog volumes during catalog recovery.
NetBackup freezes the volumes in some circumstances with write once read many (WORM) media or WORM-capable drives.
You can unfreeze the frozen volumes manually.