aac scsi raid driver performance

[Ahnjoan Amous]

Scott - I disabled read cache on both containers and the end result
for my write tests is still 25M/sec.  I have included the output to
aaccli to confirm that I disabled the correct cache.  Maybe I'm just
expecting too much from the PE2650 with PERC 3/di.  I know there are a
lot of variables in this equation but what speeds would you expect for
this U160 scsi raid controller front ending U320 devices on a box with
no load and no i/o, other than two concurrent dd's to two different
ufs mounted hardware raid 0 volumes?

Thanks
Ahnjoan

AAC0> container show cache 2
Read Cache Setting        : DISABLE
Write Cache Setting       : ENABLE WHEN PROTECTED
Write Cache Status        : Active, protected

AAC0> container show cache 3
Read Cache Setting        : DISABLE
Write Cache Setting       : ENABLE WHEN PROTECTED
Write Cache Status        : Active, protected


On 1/12/07, Scott Long <scottl at samsco.org> wrote:
> Turn off read caching
>
> Ahnjoan Amous wrote:
> > 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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> >>
> >>
>
>