I/0 issue on a poweredge 750 wit sata raid 1.

Julien Lavigne du Cadet jlavigne at kaalys.com
Sun Aug 22 11:18:35 PDT 2004


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. 



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