--- On Wed, 9/3/08, Michael Galloway <mgx AT ornl DOT gov> wrote:

> From: Michael Galloway <mgx AT ornl DOT gov>
> Subject: Re: [Bacula-users] Backup of many many files
> To: "Ryan Novosielski" <novosirj AT umdnj DOT edu>
> Cc: bacula-users AT lists.sourceforge DOT net
> Date: Wednesday, September 3, 2008, 11:03 AM
> On Wed, Sep 03, 2008 at 11:59:49AM -0400, Ryan Novosielski
> wrote:
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> > 
> > Chris Howells wrote:
> > > Michael Galloway wrote:
> > > 
> > >> how does concurency work for tape libraries?
> can i use spooling and concurrency?
> > >> would that help? i've already got
> spooling job (2GB segments) and attributes.
> > > 
> > > You can use concurrency with tape, yes. I write
> five concurrent jobs to 
> > > LTO-4. (I have an autochanger, but it's only
> got a single LTO4 tape 
> > > drive in it).
> > > 
> > > The bacula manual warns somewhat against using
> concurrent jobs with 
> > > tape, but I've been using it for a year,
> every restore has been 100% 
> > > perfect, and the restore speed is absolutely fine
> for my needs, it's 
> > > pretty quick anyway.
> > > 
> > > I'm not sure about spooling as I don't
> use it but I understand it can 
> > > help to increase restore speed, but as I said, I
> don't have a problem 
> > > with restore speed anyway.
> > 
> > You should use spooling. I'm not 100% sure that
> interleaving should even
> > be allowed, as I've heard of some people having
> strange things happening
> > with it enabled. Also takes life off your tape head,
> if I'm not mistaken.
> >
> 
> are there any recommendations on the size of the spool
> segment?

  It depends on how much disk space you have, they are cheap nowadays.

  I run five concurrent jobs and spool complete job before writing it to the 
tape. My largest backup client backs up 127 GB. I have setup 500GB filesystem 
for spool so bacula is able to spool five job simultaneously before writing 
them to tape.

  Bacula will spool five jobs at same time but write one job at a time to the 
tape.

> 
> -- michael
>  
> 
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Hemant Shah
E-mail: hjrrs AT yahoo DOT com



      

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