aac scsi raid driver performance

[Ahnjoan Amous]

I reset the controller to the defaults for everything before I did the
installation.

Each of the containers were created with the following options.
Container Type - RAID 0
Container Label - data03
Container Size - 279.396 GB
Chunk Size - 64KB
Read Caching (Yes/No) - Y
Write Caching : Enable when protected
Create RAID 5 via - N/A

Then the controller itself has a single cache option
Drives Write Cache - Disabled

Thanks
Ahnjoan

On 1/11/07, Scott Long <scottl at samsco.org> wrote:
> Did you enable read caching for the arrays?
>
> Scott
>
>
> Ahnjoan Amous wrote:
> > I'm trying to find possible explanations for slow concurrent writes
> > through the
> > aac driver.  This machine runs under 1% load and has less than 4
> > transfers per
> > second to the drives in question when not being used for testing.
> >
> > When I attempt sequential "dd"s as follow, the results are better then
> > 70MB/sec.
> >  dd if=/dev/zero of=/data02/helloworld bs=1m count=1000
> >    1048576000 bytes transferred in 13.886718 secs (75509274 bytes/sec)
> >  dd if=/dev/zero of=/data03/helloworld bs=1m count=1000
> >    1048576000 bytes transferred in 14.011323 secs (74837758 bytes/sec)
> >
> > When I attempt concurrent "dd"s as follow, with a 1 second sleep interval
> > between starts, the results are better than 40MB/sec
> >  dd if=/dev/zero of=/data02/helloworld bs=1m count=1000 &
> >  sleep 1
> >  dd if=/dev/zero of=/data03/helloworld bs=1m count=1000 &
> >    1048576000 bytes transferred in 25.269555 secs (41495626 bytes/sec)
> >    1048576000 bytes transferred in 24.935765 secs (42051086 bytes/sec)
> >
> > When I attempt concurrent "dd"s as follow, the results are little better
> > than
> > 20MB/sec
> >  dd if=/dev/zero of=/data02/helloworld bs=1m count=1000 &
> >  dd if=/dev/zero of=/data03/helloworld bs=1m count=1000 &
> >    1048576000 bytes transferred in 44.963408 secs (23320652 bytes/sec)
> >    1048576000 bytes transferred in 45.010065 secs (23296478 bytes/sec)
> >
> > I can't account for what causes the huge difference however the results are
> > reproducible.  I've run the tests dozens and dozens of times now, first
> > blaming
> > the em driver for my slow ggatec/ggated results, then GEOM for my slow
> > local
> > mirroring after eliminating the network, and finally blaming the aac driver
> > after removing GEOM from the equation.  If anyone has ideas on what I might
> > look at or change or test I would love to hear.
> >
> >
> > ****** Misc. Information ******
> > root:somehost:~ > df -k
> > Filesystem    1K-blocks    Used  Avail Capacity  Mounted on
> > /dev/aacd2s1e   2026030 1024532 839416    55%    /data02
> > /dev/aacd3s1e   2026030 1024532 839416    55%    /data03
> > Hardware -
> > aac - Dell PERC3/Di U160
> > aacd2 - hardware RAID 0, w/1 U320 300G drive
> > aacd3 - hardware RAID 0, w/1 U320 300G drive
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