Bacula-users

Re: [Bacula-users] concurrent jobs on the same storage

2010-02-24 08:09:31
Subject: Re: [Bacula-users] concurrent jobs on the same storage
From: Silver Salonen <silver AT ultrasoft DOT ee>
To: bacula-users AT lists.sourceforge DOT net
Date: Wed, 24 Feb 2010 15:07:21 +0200
On Wednesday 24 February 2010 13:38:17 Martin Simmons wrote:
> >>>>> On Wed, 24 Feb 2010 11:58:22 +0200, Silver Salonen said:
> > No, the default for devices has always been to allow only 1 job.
> 
> That's not correct.  Bacula has always been able to run multiple concurrent
> jobs to the same device, as long as the concurrency settings allow it (they
> don't by default) and all of the jobs use the same volume.  The data from 
the
> jobs gets interleaved on the volume.  See
> http://www.bacula.org/5.0.x-
manuals/en/problems/problems/Tips_Suggestions.html#SECTION003170000000000000000
> or the old manual:
> http://www.bacula.org/2.4.x-
manuals/en/main/Tips_Suggestions.html#SECTION0038170000000000000000

Are you saying that for concurrent jobs to work I have to run these different 
jobs into the same volume? It doesn't make any sense in the means of disk-
based backups.

BTW, this part is very obscure in the manual:
"if you want two different jobs to run simultaneously backing up the same 
Client to the same Storage device, they will run concurrently only if you have 
set Maximum Concurrent Jobs greater than one in the Director resource, the 
Client resource, and the Storage resource in bacula-dir.conf."

Does it means, that if the limits are 20 everywhere and theres just 2 jobs 
trying to run concurrently, the 2nd job will be waiting, because SD's 
concurrent jobs' limit is not GREATER (ie. >20) than the limit is elsewhere? 
That doesn't make any sense..

I also made a test I wrote about in the bug report:
1) I defined 2 separate storages for the 2 jobs
2) I set the storages to use the same device ("Device = device-silver"). When 
I ran the jobs, the 2nd job still got waiting "on Storage storage-silver"
3) I set the storages to use separate devices ("Device = device-silver" and 
"Device = device-silver-test"). When I ran the jobs, the jobs ran 
concurrently.

That doesn't look like a device lets 2 jobs to run on the same device.

> > I use disk-based backups, 
> > so device in my case is a folder. With device allowing only 1 job to run, 
to 
> > be able to run different jobs concurrently into the same folder (aka 
device) I 
> > have to define separate devices for every job, which seems quite.. 
redundant.
> > 
> > With device allowing multiple jobs concurrently I can define just one 
device 
> > (eg. pointing to /backup/silver) and run every job of the same client on 
that 
> > device.
> 
> No, that still doesn't work, just like it doesn't work for tape devices (a
> tape drive can't read/write more than one tape at a time).

Doesn't work why? Because disk cannot save multiple files concurrently in a 
directory?

--
Silver

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