2650 local RAID Disk Performance

[Andrey Dmitriev]

We have a Dell poweredge 2650 with either 5 in RAID5.

It's running redhat 4 update 5.

I did some basic dd tests with 8K block size, and couldn't see anything 
higher than 14.3megs per second sustained.

Is this normal? We have a 2950 with 15K SAS drives, and that thing just 
screams with around 150Megs per second... I am not expecting such high 
numbers out of an older system, but 40-60Megs would be more acceptable 
to me.


[root at mt-mail1 ~]# time dd if=/dev/zero of=/var/10g.file bs=8192 
count=1310720 
1310720+0 records in 
1310720+0 records out 
  
real    11m53.161s 
user    0m0.881s 
sys     1m11.398s

[root at mt-mail1 ~]# time dd if=/dev/zero of=/var/10g.file bs=131072 
count=81920 
81920+0 records in
81920+0 records out

real    11m42.366s
user    0m0.099s
sys     1m11.232s