On Monday 29 March 2010 12:48:14 James Harper wrote:
> > In addition, one should take care in using multipe disk Devices that
>
> write to
>
> > the same physical disk drive.  Depending how you set it up and how
>
> many you
>
> > have, you may create severe disk fragmentation and performance
>
> problems.
>
>
> I use 1 disk device per client (and 1 job per volume) and had never
> considered that fragmentation could be a problem... In retrospect I
> guess it was pretty obvious. 

For most people, it may not be so obvious, but for someone like me who thinks 
about Bacula all the time (too much), it is a concern.

> xfs_db tells me I have 99.94% fragmentation 
> - I guess it couldn't get much worse :)

Yes, I have recently run into a case, where one site is trying to 
simultaneously write to 120 different disk devices.  IMO, this is a far from 
optimum Bacula configuration.

Some sites for reasons of security or separation of data may need to use a 
different disk device per client, and that will work fine until you get up to 
50 or 100 clients, then the performance problems will begin to show up.

>
> Backup performance isn't an issue at this time but it's something to
> think about in the future.

Bacula permits sys admins to configure it in many different ways -- it is very 
flexible which is good, but can also lead to bad configurations.  However, as 
backup jobs get larger and larger over the years (bigger computers, ...), and 
the number of users increases, configurations that previously worked well 
will no longer serve.   Unfortunately, because the project is much bigger, 
certain developer's such as my self are no longer able to provide this kind 
of support, but I think that more experienced people who are on the 
bacula-users list can help a lot, and there are a good number of those 
experienced users willing to help.

Best regards,

Kern

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