Subject: Re: [Bacula-users] Speed of backups



Jason Voorhees:
> On Thu, Apr 28, 2011 at 12:01 PM, John Drescher <drescherjm@xxxxxxxxx>
wrote:
> >> So do you believe these speeds of my backups are normal? I though my
> >> Library tape with LTO-5 tapes could write at 140 MB/s approx. It
> >> isn't possible to achieve higher speeds?
> >
> > You need to speed up your source filesystem to achieve better
> > performance. Use raid10 or get a SSD. It has nothing at all to do with
> > your tape or bacula speed if you hard drive can not read what it needs
> > to backup at the maximum network speed. Or do not worry so much how
> > much time a single backup is taking and enable concurrency and
> > spooling. These will better utilize the speed of your tape drive.
> >
> >
> > John
>
> strange!, I ran a hdparm test at the fileserver (the source of backup)
> and I get a better performance:
>
> [root@qsrpsfs1 ~]# hdparm -t /dev/mapper/mpath0
>
> /dev/mapper/mpath0:
> Timing buffered disk reads: 622 MB in 3.00 seconds = 207.20 MB/sec

This is a measure for your peak i/o performance. Average performance will
be between 10% to 80% of that, depending on your file mix, moon phase and
personal karma.

To see wether the file system is indeed the bottleneck you could try to tar
the fs to /dev/null and compare the transfer rate to that of your bacula
backup.

regards,
Dietz

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