Tape Backup: understanding media sets

[marte]

I think I have a misunderstanding concerning media sets when using a tape library.

I have configured a media pool with a allocation policy "monthly" and a retention policy "2 weeks".

My understanding was, when removing the tape the backups are on from the library, a new tape gets selected with starts a new media set (thus, with a full backup), as the ols one can't be continued.

first backup works as expected (full backup):

Duration: 2h 14min 49s

Used Tapes:
KH3912L6

the second also (changes):

Duration: 6min 54s

Used Tapes:
KH3912L6

But, after removing the tape, I expected another full backup, but got:

Duration: 4min 20s

Used Tapes:
KH3913L6

So, only changes were written (at least thats what I think looking at the duration and how it gets displayed):


Why was no new media set started? In the documentation is written

Additionally, the following events may allocate a new media set:

• Required tape is offline (and you use a tape library).

Okay, it MAY start a new media set. Why it doesn't in my case?

 

[dcsapak]

Hi

just fyi, i did not forget this thread honestly i'm not sure why it did not allocate a new media-set, but could you post your allocation/retention policy of that pool, then i can look into the source and see what might be going on there
(also maybe the docs are inaccurate or theres some info there missing)

EDIT: oops, i overlooked you already posted the policies... i'll look as soon as i have some time

 

[marte]

Hi

just fyi, i did not forget this thread honestly i'm not sure why it did not allocate a new media-set, but could you post your allocation/retention policy of that pool, then i can look into the source and see what might be going on there
(also maybe the docs are inaccurate or theres some info there missing)

EDIT: oops, i overlooked you already posted the policies... i'll look as soon as i have some time

thank you!

I had already labeled some tapes for this pool, so that I can be sure which tapes can be used:

Is this maybe a problem?

Thank you & best regards

 

[dcsapak]

Is this maybe a problem?

no, that should not make a difference, it just reserves the tapes for that media-pool, not for any specific media-set

 

[marte]

no, that should not make a difference, it just reserves the tapes for that media-pool, not for any specific media-set

then that's at least consistent with my understanding

 

[dcsapak]

ok looking at the code, there are a few reasons when a new media set is created:

* if it's forced (via 'new backup' in the gui for example)
* because of the policy ( always or the time matches)
* an error with the media set happened ( e.g. missing tapes in the inventory, owner error etc. )
* the pool encryption key changed
* or if the last writable media is "vaulted" ( so marked as being in a vault)
(also maybe some reason that i missed)

though i'm questioning the last part a bit, as it does not make complete sense to me that only in the case of vaulted tapes a new media set is created.
i have to confer with my colleague though, maybe there is a deeper reason for this that i'm currently not seeing