Date: Thu, 11 Jan 2007 13:42:32 -0700 From: Scott Long <scottl@samsco.org> To: Ahnjoan Amous <ahnjoan@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: aac scsi raid driver performance Message-ID: <45A6A138.8090208@samsco.org> In-Reply-To: <5e575c8a0701111155l859d0ecif617dbda43cef842@mail.gmail.com> References: <5e575c8a0701111155l859d0ecif617dbda43cef842@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
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 > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?45A6A138.8090208>