[RndTbl] RAID5 rebuild performance

Kevin McGregor kevin.a.mcgregor at gmail.com
Thu May 19 14:52:24 CDT 2011

raid6: using algorithm sse2x2 (2883 MB/s). So, 1% of that is reasonable? :-)
Oh well, I guess I can wait until tomorrow for the rebuild to finish.

On Thu, May 19, 2011 at 2:12 PM, Adam Thompson <athompso at athompso.net>wrote:

> Look back in dmesg output for the RAID module speed tests, notice which one
> was selected, and divide that number by 2.  There's your theoretical
> bottleneck on the CPU.
> Take the minimum sustained disk/channel/controller throughput, factor in
> interrupt latency, device driver efficiency, etc. and make a rough guess as
> to the overall throughput.
> Consider that md code seems to have a lot of write barriers for safety -
>  so even a rebuild will aspens much of its time waiting for the disk to
> sync().
> All in all, I think your numbers are probably reasonable.
> -Adam
> Kevin McGregor <kevin.a.mcgregor at gmail.com> wrote:
> >I installed Ubuntu Server 10.04.2 LTS AMD64 on a HP ProLiant ML370 G3 (4 x
> >dual-core/hyperthreaded Xeon 2.66 GHz, 8 GB RAM) and I used the on-board
> >SCSI controller to manage 8 x 300 GB 15K RPM SCSI drives in a software
> >5 set up as a 7-drive array with 1 hot-spare drive. All drives are the
> exact
> >same model with the same firmware version.
> >
> >It's currently rebuilding the array (because I just created the array) and
> >/proc/mdstat is reporting "finish=165.7min speed=25856K/sec". Does that
> >sound "right" in the sense that it's the right order of magnitude? I
> though
> >it should be higher, but I haven't set up such an array before, so I don't
> >have anything to compare it to.
> >
> >If it's slow, does anyone have a suggestion for speeding it up?
> >
> >Kevin
> >
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