How does backup exec read tapes

[Bob_Barker]

I am trying to figure how backup exec writes to tapes in robotic libraries? This issue is fairly hard to explain, however will try my best...

Tapes are linear, unlike hard disk so this is where this issue starts. If I have a 200GB tape that is set to be overwritable, when there is only 20GB left and the new job is larger than the space left on the tape, will backup exec start the job at the end of the tape and finish out the 20GB left or will it go back to the beginning of the tape and start the new job?

Any feedback would be helpful. Thanks

[David_Sanz]

Bob

In that case, if the job is set to Append and the Append period is still active, Backup Exec starts appending data at the end of the tape. When the tape is finished, Backup Exec needs an overwritable one to keep on writing data. It won't use the same one, as the backup would be useless, because a backup spread amongst several tapes needs the first one to be restored.

Regards

[Ken_Putnam]

Overwrite ALWAYS starts at the beginning of the tape.

If your job is Overwrite only, Backup Exec must see a tape whose OPP has expired, or it will post an alert asking for an overwritable tape

If your job is Append/Else Overwrite, if the media set on the tape matches the media set of the job, and if APP time is left, it will begin writing at the end of the previous backup set. When/if the tape fills up, BackupExec will ask for an Overwritable tape. Continuation tapes are ALWAYS overwrite, regarless Append setting

Does this help any?

[Bob_Barker]

This makes sense, Thanks guys for your help!