2650 local RAID Disk Performance

[Andrey Dmitriev]

Looks like Write Cache was disabled..
Now getting about 20-21Megs/sec... Still slow in my book.

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    8m32.544s 
user    0m1.029s 
sys     1m15.292s 
[root at mt-mail1 ~]# 
[root at mt-mail1 ~]# time dd if=/dev/zero of=/var/10g.file bs=65536 
count=163840 
163840+0 records in 
163840+0 records out 

real    8m4.661s 
user    0m0.199s 
sys     1m14.062s 



-----Original Message-----
From: Andrey Dmitriev 
Sent: Wednesday, July 18, 2007 4:33 PM
To: linux-poweredge at dell.com
Subject: 2650 local RAID Disk Performance

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


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