Re: [Bacula-devel] [Bacula-users] 2.1.10 beta: no appendable volume found problem with multidrive autochanger

[Kern S. <ke...@si...>]

On Tuesday 22 May 2007 14:02, John Drescher wrote:
> > So to summarize my impressions:
> > There *might* be a bug in the volume-selection-code of bacula which exists 
at
> > least from V1.38 up to V2.1.10beta which leads sometimes to selecting the
> > wrong volume for a job.
> > As far as I can tell (but my vision might be clouded by the circumstance, 
that
> > I am using a multidrive autochanger myself) is, that this bug shows his 
head
> > more often (or only) when using a (multidrive) autochanger.
> > By now there are far, far to many if's, might's, and more subjunctives to 
file
> > a bug report.
> >
> I believe the problem is that if you have prefer mounted volumes on
> with multidrive autochanger bacula ends up using only the first drive
> in the changer unless you force jobs to the individual drives. 

With perfer mounted volumes on (default), as you know the algorithm will 
always select a drive that is currently mounted, however, if I am not 
mistaken, when no jobs are running and there are two drives with appropriate 
Volumes mounted, it will attempt to alternate between them, and if there are 
multiple drives actually writing, the algorithm will attempt to balance the 
number of jobs on each drive (I didn't look at the code, and this last remark 
may only apply if prefer mounted volumes is off).

> If you have prefer mounted volumes off bacula will pick any tape in the pool
> when running jobs. 

The algorithm for picking available Volumes from the correct Pool is in the 
Director, and is totally independent of the state of prefer mounted volumes 
and anything else that is going on in the SD ...

> I would say that both results are not what a user of a multitape changer 
would want.

Well that is an interesting remark.  What does a user of a multiple "drive" 
autochanger want?


Regards,

Kern