Re: [Bacula-users] Backup of many many files



--- On Thu, 9/4/08, Ryan Novosielski <novosirj AT umdnj DOT edu> wrote:

> From: Ryan Novosielski <novosirj AT umdnj DOT edu>
> Subject: Re: [Bacula-users] Backup of many many files
> To: bacula-users AT lists.sourceforge DOT net
> Date: Thursday, September 4, 2008, 8:31 PM
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> Jose Ildefonso Camargo Tolosa wrote:
> > Hi!
> > 
> > I have to answer on this....
> > 
> > On Fri, Sep 5, 2008 at 12:03 PM, Hemant Shah
> <hjrrs AT yahoo DOT com> wrote:
> >>
> >> --- 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:
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> >>>> 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.
> > 
> > Yes, but not every "cheap" hard drive will
> be able to give you the
> > throughput to keep the tape writing continuously, for
> example, a LTO-4
> > drive that I tested a few weeks ago, gave ~100MB/s
> write speeds, and
> > the server that had it attached only went up to 70MB/s
> hard drive read
> > speed (sequential).
> 
> That's an interesting question. I'll have to take a
> look at my
> configuration and see how I do.

  If the drives are RAID/SAN configured then you should get better through put. 
Backups are very I/O intensive (disk, network, etc), so it is tricky to 
maximize the I/O device throughput. 

 
> 
> > So, I decided to use tmpfs, ~ 1.5GB (I only had 2GB
> available :( ).
> > 
> > I have read lots of posts stating huge spool size, but
> I'm not sure if
> > they tested they hard drive performance compared to
> the tape's
> > performance.
> >
> > I know this has been previously discussed on the list
> (that's where I
> > got the idea of using tmpfs), but I thought it could
> be a good idea to
> > bring this issue to this thread.
> 
> - --
>  ---- _  _ _  _ ___  _  _  _
>  |Y#| |  | |\/| |  \ |\ |  | |Ryan Novosielski
> - Systems Programmer II
>  |$&| |__| |  | |__/ | \| _| |novosirj AT umdnj DOT edu -
> 973/972.0922 (2-0922)
>  \__/ Univ. of Med. and Dent.|IST/AST - NJMS Medical
> Science Bldg - C630
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Hemant Shah
E-mail: hjrrs AT yahoo DOT com


      

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