On Fri, Oct 01, 2010 at 08:07:27PM +0200, Sylvain MAURIN wrote:
> Why didn't you check the amount of the IO ? FS bottlenecks,
> particulary BackupPC heavy inode seeking, are *never* a result 
> of disk bandwith.
> 
> Your choice of RAID 5, is really a pain in IO domain
> if u don't take a lot of time in striping optimization.
I understood that.  This is only to backup 4 desktops and 3 remote
servers.

> My advice : do an iotop/iostat -mtx 3 and find out 
> where is your problem. I am ready to bet that you
> rarely have large sequential access if you backup many
> desktop systems and around 2Mb you are closing 500 IO/s
> that most RAID 5 Subsytems can provide.

I'm getting about 1500 IO/s throughput at the moment.  Sometimes higher

Device:         rrqm/s   wrqm/s     r/s     w/s    rMB/s    wMB/s avgrq-sz 
avgqu-sz   await  svctm  %util
md3               0.00     0.00  472.00 1954.67     3.67     7.64 9.54     0.00 
   0.00   0.00   0.00

The biggest change is that the second full backup performed after
turning off compression is 5 times faster (118 m) than the previous 5
backups (4 w/compression, 1 w/o compression) (450 - 700 m each).

I'm hoping that that means rsync is doing it's job and unchanged files
are not being transferred now.

-- 

Wayne Walker
wwalker AT solid-constructs DOT com
(512) 633-8076
Senior Consultant
Solid Constructs, LLC

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