freebsd stable - Aug 2004 - I/0 issue on a poweredge 750 wit sata raid 1.

Hi eveybody,

 

I've been using Freebsd 4.x for more than 6 months now, with a very common
system (P4 2,4 - 1Go ram - ide hdd). As I've been very pleased with this OS,
I'd like to use it with one of our new server, a dell poweredge 750, P4 3,2
- 1Go ram -  2 sata drives on a raid 1 array.

 

So I installed Freebsd 4.10 on it, and everything went well during the install.
But I started a few tests (this machine is supposed to be a web server), and
I've been very disappointed by the I/0 performances. In fact, the same query
on the same database takes 2,56s on my old P4 (which supports about 300 persons
on a vbulletin forum at the same time), and 4,80s on the new dell. Of course,
the mysql configuration is the same, and I've launched the query a few time
to avoid differences due to mysql cache.

Moreover, the new server has been partitioned following the FreeBSD standards,
and softupdate is on whereas the old server doesn't have it.

 

My guess is that it's related to raid and/or sata support on FreeBSD 4.10
but I was not able to find much about it on google. The only thing interesting,
was on the aac man page, which recommends to add a var to loader.conf for
maximum performances (what I've done but it didn't make a difference).

 

I didn't make any tuning of things like that. The only thing that's
I've done is to build a new kernel with CPU_ENABLE_SSE and without I386_CPU,
I486_CPU, I586_CPU.

 

Any advice would be greatly appreciated,

Best regards,

Julien Lavigne du Cadet.

Julien Lavigne du Cadet writes:
| So I installed Freebsd 4.10 on it, and everything went well during the
install. But I started a few tests (this machine is supposed to be a web
server), and I've been very disappointed by the I/0 performances. In fact,
the same query on the same database takes 2,56s on my old P4 (which supports
about 300 persons on a vbulletin forum at the same time), and 4,80s on the new
dell. Of course, the mysql configuration is the same, and I've launched the
query a few time to avoid differences due to mysql cache.

	http://www.ambrisko.com/doug/ata

Should help you.

Doug A.