On 22/07/10, John Drescher (drescherjm AT gmail DOT com) wrote:
> On Thu, Jul 22, 2010 at 7:07 AM, Rory Campbell-Lange
> > I am now using a spool to see what is happening for the locally attached
> > Coraid storage. The locally attached storage runs at a (contended) write
> > of 77MB/s and read of over 100MB/s as confirmed by the tool ddt.
> >
> > So I now have a Full backup running off local attached storage (Coraid,
> > ext3) to fully local storage (HW RAID with BBU, xfs). However bconsole's
> > "status client" still shows activity at around 20-30MB/s
> > (Bytes/sec=24,363,733) with bacula-fd reading off the target at around
> > 20-30MB/s to make a local 250GB file. Incidentally, ?bacula-sd
> > periodically writes to tape at ~ 100MB/s.
...
> > Is there a problem with bacula-fd?
> >
> Have you disabled software compression in your fileset? Also random
> filesystem performance even on a raid is not great. While you may be
> able to read 500MB/s sequential data if the files needed to backup are
> not physically ordered sequentially the rate will greatly reduce. Are
> you doing a Full Backup? Is your spool on a different raid than the
> source data? If the spool is on the same raid this will cause further
> reduced performance because it will be causing more seeks again and
> reducing the large sequential operations.

I have disabled software compression and the backup is a Full backup as
noted above.  The spool is local, the file system being backed up is on
a Coraid (ethernet-attached) file system.

Your point about non-sequential file access is a good one. Nevertheless
20MB/s is very poor performance. 

-- 
Rory Campbell-Lange
rory AT campbell-lange DOT net

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