Could I ask why "Media Unmount Delay" is needed?

[JeffreyW]

I don't know why "Media Unmount Delay" is needed. Is there advantage?

Why had this option been maded in Netbackup and had default value "180 seconds"?

In addition, When a backup job is completed, does Netbackup check the unload success from a library after Netbackup request unload to a library?

Or, how does Netbackup check the unload success of media from a library? 

[mph999 · Accepted solution]

It is there for you to leave the tape in te drive for a specified amount of time after a job has completed.  This allows further jobs that may use the tape to do so withouty it being unloaded/ reloaded.

If an unload fails, the drive / robot will 'report' an error and send out eithe an 'ASC/ ASCQ' SCSI status, or perhaps a Tapealert.  NBU detects these and will log if a failure happens.

Martin

[Yasuhisa_Ishika]

To avoid unnecessary unmount and remount between user backups and restores, NetBackup keeps tape mounted within this delay. If NetBackup unmount tape immediately after job completion, NetBackup will mount and unmount tape several times in single oracle backup session - oracle backup raises multiple user backup requests at one time. By Administrator's Giude: To specify a Media unmount delay property indicates that the unloading of media is delayed after the requested operation is complete. Media unmount delay applies only to user operations, to include backups and restores of database agent clients, such as those running NetBackup for Oracle. The delay reduces unnecessary media unmounts and the positioning of media in cases where the media is requested again a short time later.