The Admin Guide is your friend:
Admin Guide for UNIX,Linux, I http://www.symantec.com/docs/TECH127081
Admin Guide for Windows, I http://www.symantec.com/docs/TECH127079
About frozen media
Suspending or unsuspending a volume
Please let us know if you have more questions once you've read these topics in the manual.
Lots more info if you search this forum, such as: https://www-secure.symantec.com/connect/forums/difference-between-suspended-and-frozen-media#comment-3966341
or Google: http://www.symantec.com/docs/HOWTO43669 ..........
Suspended media will no longer be used, whilst it contains valid backups. Once the last backup on the media has expired, the media will expire and will be availble to NetBackup.
Frozen media will no longer be used at all. The tapes will not be released for re-use once their expire date is passed.
You cannot suspend or freeze a tape if it has no assign time (which basically means if it contain no images).
And now the most important bit ....
Tapes/ media should never be frozen manually - no exceptions, unless support ask you to.
Customer has an issue where many media are frozen.
Media are frozen by netbackup if 3 errors/ 12 hours are detectedm but forget the details, here is the simplified version - NBU freezes media if it thinks it is bad/ has errors.
Due to the possibility of frozen media causing damage to drives if re-used (yes, it does happen ...) then Symantec can never recommend to unfreeze media, unless, we can prove that the media has been frozen for some 'harmless reason' (for example, media will be frozen if it is set as read-only, clearly, this media is safe to re-use).
So, if tapes are manually frozen, and some time passes, and perhpas the customer forgets he has frozen the media/ leaves the company etc ... you end up with x number of media that Symantec cannot proves the reason it was frozen - and therefore, it cannot be recommneded the media is reused.
Thanks to you all for the inputs that you have provided.
When is the time assigned to a tape or media. Is it when data is written first time on the tape or it is when you assign it to a Volume Pool because i assume the retention period starts from the assigned time of the media. CAn anyone explain to me as i'm a bit confused.
Assign time is when a tape is first allocated for a backup. More or less the same time that you see resource allocation happening in Details tab of Activity Monitor. More or less the same time as first being written to (a minute or so difference...)
Have a look at all the fields displayed in output of the following command for one of your Assigned tapes:
nbemmcmd -listmedia -mediaid <media-id>
Please also bear in mind that multiple backups can be written to a tape. So, if you leave tapes in the robot and do not suspend manually after being used, the following happens:
Example - Daily Inc backups with retention of 2 weeks:
Monday 1 Aug 19:00: New tape is used. Assign Time: Monday 1 Aug 19:00 Expiration: 15 Aug +-19:00
Tuesday 2 Aug 19:05: Same tape is appended to. Assign Time stays the same. Tape expiration is now 16 Aug +- 19:05
Tape is now full and no more backups are written to this tape. Last images on this tape expire on 16 August +- 19:05, but Image Cleanup only runs every 12 hours. At the next cleanup cycle after expiration date/time, the media will be deassigned.
Martin is our 'resident tape expert' and will probably be able to explain this a lot better!