Re: looking for a transparent hardware RAID controller for debian
On Thu, 2005-11-10 at 08:37 -0800, David Kirchner wrote:
> On 11/10/05, Ron Johnson <ron.l.johnson@cox.net> wrote:
> > The issue was performance, though. Are you getting good speed?
>
> I must have missed that email then, sorry about that. We use RAID5 on
I don know if it was my message, but I am having major performance
problems in PostgreSQL doing long *updates* (NOT inserts) in largish
tables (1.100.0000 records). In general I see only ~100/200
writes/second, totaling ~2000/3000 KILOBYTE/second.
Reading and (batch) inserts perform reasonable well. This all on a
Debian Sarge Testing 2.6.12-1-amd64-k8-smp, 2 Opteron 248, 4GB, 5 disk
RAID5 array with a 3Ware 9500S-8
> $ dd if=/dev/zero of=/data2-2/bigfile bs=131072 count=100000
> 100000+0 records in
> 100000+0 records out
> 13107200000 bytes transferred in 119.269480 seconds (109895675 bytes/sec)
jkr@Panoramix:~/tmp$ dd if=/dev/zero of=/home/jkr/tmp/bigfile bs=131072 count=10000
10000+0 records in
10000+0 records out
1310720000 bytes transferred in 14.468310 seconds (90592473 bytes/sec)
I did notice that changing the I/O scheduler's nr_request from the
default 128 to 1024 or even 4096 made a remarkable performance
improvement. I suspect that experimenting with other I/O schedululers
could improve performance.
More more info see also:
http://www.issociate.de/board/goto/894541/3ware_+_RAID5_
+_xfs_performance.html#msg_894541
http://lkml.org/lkml/2005/4/20/110
http://seclists.org/lists/linux-kernel/2005/Oct/1171.html
--
Groeten,
Joost Kraaijeveld
Askesis B.V.
Molukkenstraat 14
6524NB Nijmegen
tel: 024-3888063 / 06-51855277
fax: 024-3608416
e-mail: J.Kraaijeveld@Askesis.nl
web: www.askesis.nl
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