Hi Holger,
Based on short session of troubleshooting, I believe the machine actually
suffer from low I/O speed to the disk. Average read is about 3 MB/s, which
I considered slow for a SATA disk in IDE emulation.
I'm planning to suggest to the customer to have a RAID 1 setup to increase
the I/O speed. I'm looking at possibilities to speed things up by not
having to change the overall setup.
Thank you for providing new insights to me regarding rsync. Glad to learn
new things :)
Thanks.
On Thu, Oct 31, 2013 at 5:15 AM, Holger Parplies <wb...@parplies.de> wrote:
> Hi,
>
> Adam Goryachev wrote on 2013-10-29 15:29:42 +1100 [Re: [BackupPC-users]
> rsyncd full backup]:
> > On 29/10/13 15:14, Sharuzzaman Ahmat Raslan wrote:
> > > [...]
> > >On Tue, Oct 29, 2013 at 11:33 AM, Les Mikesell <lesmikes...@gmail.com
> > ><mailto:lesmikes...@gmail.com>> wrote:
> > > On Mon, Oct 28, 2013 at 10:08 PM, Sharuzzaman Ahmat Raslan
> > > <sharuzza...@gmail.com <mailto:sharuzza...@gmail.com>> wrote:
> > > > [...]
> > > > Initially, the backup transport is SMB, but recently, I noticed
> > > > a lot of machine backup (full and incremental) is not able to
> > > > complete in 8 hours, due to large number of file, and big file
> size.
> > > >
> > > > Last week, I installed DeltaCopy (rsycnd server for Windows) on
> > > > one machine, and change the backup transport to rysncd. The backup
> > > > runs well.
> > > >
> > > > But today, I noticed, when BackupPC is running a full backup on
> > > > the machine that have rsyncd, it still takes 8 hours to do full
> > > > backup. [...]
> > > Rsync will only transfer the changed data, but in full runs the
> > > contents of the files are read at both ends and compared with block
> > > checksums, so it takes some time. [...]
> > >
> > >In essence, if I enable
> > >|--checksum-seed=32761
> > >
> > >|
> > >then the rsync full backup will be faster?
> >
> > Yes, the third full backup after you enable that option will be faster
> > *IF* the slow speed is due to the backup server needing to decompress
> > the file and check the content.
>
> let me stress that again: don't expect a speedup on the *first* full backup
> after you enable that option. In my limited opinion (I haven't compared
> speeds
> because I don't have any issues with slow backups), the *second* full
> backup
> should be faster, as you have pre-existing full backups, i.e. the next full
> can add the checksums. In any case, the *third* full backup should
> hopefully
> be faster :-).
>
> > In the case that your backup client has really slow disk, then there is
> > nothing you can do, except maybe modify backuppc for full backups to not
> > send the ignore-times option to rsync (ie, every backup is an
> > incremental). Or, of course, upgrade the client to improve performance.
>
> Actually, it is worth noting that aside from a possible speed improvement
> the
> switch from smb to rsync(d) gives you far more precise *incremental*
> backups,
> so it might be an option to increase FullPeriod. This may transfer more
> data
> (because the delta is always relative to the reference backup - normally
> the
> previous full backup - and not to the previous incremental backup), but you
> can always explore the IncrLevels setting. So, while you might not speed up
> the full runs, you might get away with doing them less often. I would not
> recommend patching the ignore-times option away altogether.
>
> But Adams point is correct: you need to find out where the problem is,
> before
> you can fix it. While you might be able to find the problem by trying out
> fixes, that might not be the most efficient way :-).
>
> Regards,
> Holger
>
>
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--
Sharuzzaman Ahmat Raslan
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