On 2013-12-19 12:06 PM, Greg Woods wrote:
> On Thu, 2013-12-19 at 11:02 -0500, Dan Langille wrote:
>> There was a lot in the above and I couldn't parse it all
>> just now.
>
> Sorry about that; I suppose it would help if I just explicitly stated
> what I really want. I have a main backup pool where all the backup jobs
> write. This pool is manually copied to the archive pool using Copy
> jobs.
> What I want is for volumes in the main pool to be recycled relatively
> quickly (because space is limited), while the files are retained much
> longer in the archive pool. I'd like restore attempts to automatically
> figure out when the files are still available in the backup pool and
> use
> it when possible, but get them from the archive pool if necessary.
> That's what I'm working toward.
Let others review this suggestion before trying it:
I set my FILE and JOB retentions high. 3 years. Then I set my VOLUME
retention lower. Whichever retention period expires first, that's the
one which counts. <== I will refer to that as 'first one counts' later
in this email.
Therefore, in your archive pool, set your VOLUME retention to 3 years,
for example.
And in your main pool, set it to 5 weeks, for example.
Does that help?
>> Instead, I'll point you to something I wrote a few years ago.
>> If you have questions after that, please ask again.
>>
>> http://dan.langille.org/2010/02/08/bacula-retention-periods/
>
> OK, good. It's good that we're having this discussion. If I understand
> any of this at all (which I may not), there are a couple of things in
> there that seem not to match my experience so far. For instance, in
> that
> document it says "you can’t restore a given file after the File
> retention passed". But that's not really true. You can't restore it in
> the "usual" way, by marking files, presumably because the list of
> available files for marking is created using those File records that
> aren't there any more.
The next sentence in my post is: If the Job retention has not passed,
you can still restore the whole job.
So yes, you have it right.
> But you *can* restore those files by using a
> regular expression; I've had to do this because I have lost a lot of my
> File records by initially setting File Retention too low. I'm not sure
> how it actually does this, but there must be some information written
> to
> the backup volume itself that can be used to determine what files are
> there. It's much slower than a database access, but I have restored
> directory trees and individual files this way.
That's interesting.
> > The document also says "Volumes are eligible for recycling once ALL
> retention periods have passed." But that doesn't seem to be true
> either; I have apparently seen Bacula recycle some volumes even though
> the Job retention period has not passed. Which means, presumably, that
> there are Job records in the database that point to backup files that
> aren't there any more, since the Volume has been recycled.
Yes, that statement seems to be wrong. As demonstrated by my 'first
one counts' claim above.
>>> Perhaps the Recycling Algorithm will help:
>>
>> http://www.bacula.org/en/dev-manual/main/main/Automatic_Volume_Recycling.html
>
>
> That does help, and I've looked at this before, but it's not always
> clear (to me) exactly how it works, even after reading that.
>
> I notice that the paragraph on Automatic Pruning says that you can't
> restore files once the File records are gone, but I know that's not
> true
> because I have done it. I suspect the documentation may be a few
> versions old and I can't necessarily trust everything it says.
You've done it a different way. Not the 'usual way'.
> It also states that when volume recycling happens, "all Jobs that are
> older than the VolumeRetention period will be pruned", presumably
> regardless of what I set for Job Retention, which leads to some of my
> confusion about what these retention periods really mean. It's even
> more confusing (to me) when you throw in Copy jobs, so that the same
> files may be on multiple Volumes in different pools.
Does what you've observed make sense when you consider my claim of
'first one counts'? I am sure that is mentioned in the docs.
--
Dan Langille - http://langille.org/
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