On Tue, Sep 18, 2012 at 10:24 AM, Timothy J Massey <tmas...@obscorp.com> wrote:
>
> Fortunately, BackupPC is a "backup of the backup" right now, and is not
> expected to be used for real. Yet. That's why I can take the time and try
> to actually solve the problem, rather than apply band-aids.
>
> But that will likely end in November, if not sooner.
It is more than a band-aid to have a warm-spare disk ready to pop in
instead of waiting for a 3TB restore even with reasonable performance.
Be sure everyone knows what they are losing.
> I'm not. I've got two of these new boxes built. In both cases, they have
> 2-4% wait time when doing a backup. One is a RAID-5 and one is a RAID-6.
Can you test one as RAID10? Or something that doesn't make the disks
wait for each other and likely count the time against the CPU?
> Might it have something to do with md? Could the time that would normally
> be considered wait time for BackupPC be counted as CPU time for md? That
> doesn't seem logical to me, but I can say that there just isn't any wait
> time on these systems.
Not sure, but I am sure that raid5/6 is a bad fit for backuppc
although good for capacity.
> > Mine seem to track the target host disk speed more than anything else.
> > The best I see is 208GB with a full time of 148 minutes. But that
> > is with backuppc running as a VM on the East coast backing up a target
> > in California and no particular tuning for efficiency. Compression is
> > on and no checksum caching.
>
> That's the same settings I'm using. But that's about double the
> performance I'm getting. 247GB in 340 minutes, or about 12MB/s.
I see more like that when backing up slower targets - the rsync
protocol probably isn't very good about overalapping the read/compare
while walking the tree with the block-checksum comparison so you add
up every little delay at either end. Are you sure the target has no
other activity happening during the backup?
--
Les Mikesell
lesmikes...@gmail.com
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