There are a couple of things you can do in combination to get the result 
you want...

First off, in your pool set a 'volume use duration' - this will restrict 
how long a time span of data can exist on a tape.  For instance in your 
case you could set the volume use duration to 32 days, this would tell 
Bacula not to append any data to a tape 32 days after the first data was 
written to it.  The tape will get a status of 'USED' rather than 
'APPEND' once that time period passes.  Regardless of what happens with 
the expiry / purge jobs this will prevent the scenario you are 
describing from ever happening - Bacula would instead complain that it 
could not find a tape if one wasn't available, it would not append data 
to an 'old' tape until the jobs on it were purged.

Secondly yes, set the volume retention lower.  Bacula will not purge a 
tape unless it needs to so it won't automatically purge data when it 
hits the volume retention date - even if you did need data off of a tape 
that was 11 months and 28 days old but Bacula hadn't needed the tape for 
writing yet, the data would still be there so you won't be loosing anything.

Bryn

On 14-10-15 09:45 AM, Thorsten Reichelt wrote:
> Hi!
>
> I have a problem with my tape pool configuration.
> I want to use exactly 12 LTO tapes (one tape per month).
> After 12 month the oldest tape shall be reused without appending new data.
>
> But bacula seems to ignore my recycle and purge configuration (see below).
> After one year I reuse the old tape and bacula appends the new data to it.
> Then, after the second year has passed, the data is still appended to
> the tape!
>
> Now I have the problem that my september tape ran out of free space and
> I was
> asked to insert the august tape... a few MB later that tape was full
> also and
> bacula asked for the july tape.... :/ :/
>
> So I manually purged the september tape and restarted all related backup
> jobs.
> How can I configure bacula to purge the oldest tape instead of appending
> to it
> for more than two years?
>
> My pool configuration for the tape looks like this:
>
> # ======================
> Pool {
>    Name = MonthlyTape
>    Use Volume Once = no
>    Pool Type = Backup
>    AutoPrune = yes
>    Recycle Current Volume = yes
>    Volume Retention = 12 month
>    Recycle = yes
> }
> # ======================
>
> Would it make sense to set the retention time to "11 month 1 days"?
>
> Thank you very much!!
>
>    Thorsten
>
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