Re: [Bacula-users] Automatic Tape Recycling

On 25.07.2012 17:50, Phil Stracchino wrote:

i think we need to understand more about the use cycle for these volumes. Are these weekly tapes written to once per week with a single job or set of jobs, or are they continuously appended to over the course of a week?

Let's just take a look at the daily backups, and only those that fit on one tape. (My problem is not limited to those, but it'll make it simpler to explain.)

There is a SET of jobs for every night, backing up different machines to the same tape one after another. The next morning, the tape is being swapped out for the next day's tape. Tapes are supposed to be re-used every week, so there is a "monday" tape, a "tuesday" tape, and so on, and the old expired backup from the preceeding week that's still on it is supposed to be automatically overwritten.

However, when the last job of the night finishes, and there's still room on the tape, bacula will leave the volume in "appendable" state. And when the tape is re-inserted the next week to be overwritten, bacula insists to append to it - no matter what the "max use duration" and the volume retention period is. And the only way to prevent this is to manually update the volume status to "used".

This is actually documented. Why "max use duration" won't work is described in

http://www.bacula.org/5.0.x-manuals/en/main/main/Configuring_Director.html

Quote: "The use duration is checked and the Used status is set only at the end of a job that writes to the particular volume".

and why bacula will never overwrite "appendable" volumes is described in

http://www.bacula.org/5.0.x-manuals/en/main/main/Automatic_Volume_Recycling.htmt (Quote: " A key point mentioned above, that can be a source of frustration, is that Bacula will only recycle purged Volumes if there is no other appendable Volume available, otherwise, it will always write to an appendable Volume before recycling even if there are Volume marked as Purged.")

And yes, thank you, it IS a source of frustration :)

The documentation offers a solution for single-job-backups ("UseVolumeOnce"), but that won't work for me because I have more than one job to go into that volume.

So, what do I do? Give up? Write a perl script that tries to figure out which volume is inserted, recycle it by hand, and run it as a high-priority admin job before the actual backup? Any less hack-ish way?

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