Re: [BackupPC-users] backuppc slow rsync speeds

Les Mikesell <lesmikesell AT gmail DOT com> wrote on 09/18/2012 12:42:26 PM: > On Tue, Sep 18, 2012 at 10:24 AM, Timothy J Massey > <tmassey AT obscorp DOT 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.

That is a good point, but if I ever have to do a full 3TB restore from BackupPC, the 12 hours a (properly performing) BackupPC will take is not my biggest issue. I don't look at BackupPC as my bare-metal disaster recovery plan--or, at least, not my first line of such defense. That's what snapshots and virtualization provides. BackupPC is for file-level restores, and the odds of having to do a full restore from BackupPC is small.
> > 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?

Unfortunately, both of these boxes are in production, so they can't be reconfigured; and I don't have enough parts for another one just yet. It is something worth trying. I predict that this won't make that much of a difference: I've tested small-write performance differences between single-disk, RAID 1, RAID 10 and RAID 5 (but not RAID 6) before, and the penalties, while very real, were also very manageable.

But I'll see if I can try it again.
> > 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.

And frankly, capacity is what I need more, with a certain minimum amount of performance. I do not need top-performance, and am perfectly willing to sacrifice performance for capacity, as long as I could get, say, 50MB/s of BackupPC throughput.

50MB/s performance for a RAID-5/6 array should not be difficult, even with read/modify/write and small transactions. I thought I had tested this workload on this array successfully, giving me more like 80-100MB/s on synthetic benchmarks.

But again, I'll see what testing I can do.
> Are you sure the target has no > other activity happening during the backup?

I am sure they *are* seeing other activity: they're file servers, mail server, etc. But their loads are all very low across the board.

Timothy J. Massey


Out of the Box Solutions, Inc. Creative IT Solutions Made Simple! http://www.OutOfTheBoxSolutions.com tmassey AT obscorp DOT com		22108 Harper Ave. St. Clair Shores, MI 48080 Office: (800)750-4OBS (4627) Cell: (586)945-8796

------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and 
threat landscape has changed and how IT managers can respond. Discussions 
will include endpoint security, mobile security and the latest in malware 
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/

_______________________________________________
BackupPC-users mailing list
BackupPC-users AT lists.sourceforge DOT net
List:    https://lists.sourceforge.net/lists/listinfo/backuppc-users
Wiki:    http://backuppc.wiki.sourceforge.net
Project: http://backuppc.sourceforge.net/