Media Usage Query

[marcymarc]

Could someone explain the rule to which NetBackup selects tapes for backups?

For example if you have partially written tapes in a tape library and also scratch tapes available?

Marc.

 

[comtec17]

Netbackup uses tapes within the same volume pool and if none are available in the volume pool it will use a scratch tape.

Now for the tricky stuff.

Netbackup will use a tape as long as the same retention period is used and is within the time of the tape. For example, Monday night @ 8pm a backup kicks off and writes to tape xyz111 and finishes around 11:15pm. No other backups write to that tape the rest of the night. Now on Tuesday the backup kicks off again, media xyz111 will not be used since the image on the tape does not expire until your retention period for the backup is met, say 10 days from now @ 11:15.

Now if your backup kicks off say Monday at 10:00pm and writes to media xyz112 and finishes around 12:01am Tuesday. Now on Tuesday your backup kicks off at 10:00pm and it will write to media xyz112 since the image last written to tape was after midnight making the tape available for use today.

Hope this helps.
CoMteC17

 

[marcymarc]

Thanks

 

[bswip]

You can also change the Global policy so that a tape can have mixed retention periods.