Hello,
I think this might be useful information, and am also hoping for a
little input.
We've been doing some FreeBSD benchmarking on Dell PE2950 systems with
Perc6 controllers (dual-quad Xeon, 16GB, Perc6=LSI card, mfi driver,
7.0-RELEASE). There are two controllers in each system, and each has
two MD1000 disk shelves attached via the 2 4x SAS interfaces. (so 30PD
available to each controller, 60 PD on the system).
My baseline was this - on linux 2.6.20 we're doing 800MB/s write and
greater read with this configuration: 2 raid6 volumes volumes striped
into a raid0 volume using linux software raid, XFS filesystem. Each
raid6 is a volume on one controller using 30 PD. We've spent time
tuning this, more than I have with FreeBSD so far.
Initially I was getting strangely poor read results. Here is one
example (before launching into quicker dd tests, i already had similarly
bad results from some more complete iozone tests):
time dd if=/dev/zero of=/test/deletafile bs=1M count=10240
10737418240 bytes transferred in 26.473629 secs (405589209 bytes/sec)
time dd if=/test/deletafile of=/dev/null bs=1M count=10240
10737418240 bytes transferred in 157.700367 secs (68087465 bytes/sec)
To make a very long story short, much better results achieved in the end
by simply by increasing the filesystem blocksize to the maximum (same dd
commands). I'm running a more thorough test on this setup using iozone:
#gstripe label -v -s 128k test /dev/mfid0 /dev/mfid2
#newfs -U -b 65536 /dev/stripe/test
#write: 19.240875 secs (558052492 bytes/sec)
#read: 20.000606 secs (536854644 bytes/sec)
Also did this in /boot/loader.conf - it effected nothing very much in
any test but the settings seemed reasonable so I kept them:
kern.geom.stripe.fast=1
vfs.hirunningspace=5242880
vfs.read_max=32
Any other suggestions to get best throughput? There is also HW RAID
stripe size to adjust larger or smaller. ZFS is also on the list for
testing. Should I perhaps be running -CURRENT or -STABLE to be get best
results with ZFS?
-Ben
--
Benjeman Meekhof - UM ATLAS/AGLT2 Computing
[EMAIL PROTECTED]
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