Veritas NetBackup™ Administrator's Guide, Volume I

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.

  Additional information about the nbemmcmd is available in the NetBackup Commands Reference Guide:

  http://www.veritas.com/docs/DOC5332

• 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.

  See About using volume pools to manage WORM media.