Slow Write Performance on 3ware controller

[Richard Collyer]

Hello,

I recently installed a 3ware 9500S-12 along with 3 x 250GB Seagate 
7200.10 Drives.

I am getting very poor read/write performance on this array that I have 
set up (RAID5 - 64K stripe)

Reading to the 2 mirrored drives that I have on a 3ware 7006-2 I can get 
  8MB/sec over samba which is what I expect. From the new array I am 
getting 4MB/sec. To rule out samba I did a file copy from one array to 
the other an averaged 3.8MB/sec which I assume is being limited by the 
new array.

Any ideas where I can check to see if there are problems and what are 
the first steps / common things that people miss when adding drives.

In short I...

a) installed the drive
b) disk partitioned using /stand/sysinstall
c) labelled using the same
d) edited /etc/drivetabthingy to mount the drive

Anyone else have any other suggestions on what I can check?

Cheers
Richard