Bacula-users

Re: [Bacula-users] About retention, and pruning.

2011-04-29 05:19:14
Subject: Re: [Bacula-users] About retention, and pruning.
From: Hugo Letemplier <hugo.let.35 AT gmail DOT com>
To: Jérôme Blion <jerome.blion AT free DOT fr>
Date: Fri, 29 Apr 2011 11:11:24 +0200
2011/4/29 Jérôme Blion <jerome.blion AT free DOT fr>:
> On Thu, 28 Apr 2011 17:33:48 +0200, Hugo Letemplier
> <hugo.let.35 AT gmail DOT com>
> wrote:
>> After the job ran many times: I have the following volume <=> job
> matching
>> Vol name   Level      Time
>> Test1         Full        15:50
>> 324            Inc         16:00
>> 325            Inc         16:10
>> 326            Inc         16:20
>> 324            Inc         16:30
>> Test2         Full        16:40
>> 325            Inc         16:50
>> 326            Inc         17:00
>>
>> This is problematic because Vol324 is recycled instead of creating a new
>> one
>> I am not sure to understand the various retention periods : File, job,
>> volume
>> I think that I can increase the retention times but the problem will
>> always be the same.
>> ex : if I keep my incremental one hour then my first ones will always
>> be purged first
>> In a good strategy you purge the full sequence of incremental at the
>> same time because you need to recycle you volume and don't want to
>> keep a recent volume (incremental) without the previous ones.
>
> You would waste your tape/disk space.
>
>> To do that I imagine that I need to create one pool per day and reduce
>> progressively the retention periods. It doesn't makes sense !
>>  I turned the problem on all its sides but I cant find a good
>> solution. Maybe the other retention period are the solution but I
>> didn't succeeded ?
>> Thanks in advance
>
> That means that your upper backup levels should have greater retentions to
> be sure that at any time, you can use the full + diff + inc if needed.
> Keeping incremental without full backup can be useful to restore only
> specific files.
Yes, but this problem is the same between incremental backups:
Lots of people recommended me to use one pool per level:
It works for Full and differentials, but not for inc pool
Maybe one inc-pool per "incremental run of a scheduling cycle" should
be good ? But it 's not simple
I think that a new feature that add dependency between various job
levels for the next versions of bacula could be cool.
The idea is to allow pruning only for volume/jobs that aren't needed
by other ones whatever are the retention time.
As a consequence : you can prune a full only (((if the differential is
pruned) if the XXX incrementals are pruned) if the last incremental is
pruned )
So you you can say that the maximum retention time for a full is at
least equal to the retention time of the last inc + the delay between
the full and the this last inc so you have something like this :
full  : ========================>>>>>>>>
inc  :   =========>>>>>
inc  :     =========>>>>
inc  :       =========>>>
inc  :         =========>>
inc  :           =========>
inc  :             =========
diff  :               ================>
inc  :                 =========>>>>>
inc  :                   =========>>>>
inc  :                     =========>>>
inc  :                       =========>>
inc  :                         =========>
inc  :                           =========
diff  :                             ================>
inc  :                               =========>>>>>
inc  :                                 =========>>>>
inc  :                                   =========>>>
inc  :                                     =========>>
inc  :                                       =========>
inc  :                                         =========

and not like that :
diff  : ==================>
inc  :   =======>
inc  :     =======>
inc  :       =======>

What do you think about such a feature ?

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