Hi,
I have a HP DL185 G6 Server (12 disk model) with the following spec:

• Quad Core Xeon 2.27GHz
• 6GB RAM
• HP P212 RAID controller with battery backup
• 2 x 128GB 15K SAS 3.5" (RAID-1 for the operating system)
• 4 x 750GB 7.5K SAS 3.5" (RAID-5 for the data, 2TB usable space)

The operating system is Ubuntu Server 9.10. Both drives have been formatted as EXT4.

We are finding that read speed of the RAID-5 array is poor. Disk test results below:

sudo hdparm -tT /dev/cciss/c0d1p1
/dev/cciss/c0d1p1:
Timing cached reads:      15284 MB in  2.00 seconds = 7650.18 MB/sec
Timing buffered disk reads:   74 MB in  3.02 seconds =  24.53 MB/sec

For info, the RAID-1 array performs as follows:

sudo hdparm -tT /dev/cciss/c0d0p1
/dev/cciss/c0d0p1:
Timing cached reads:      15652 MB in  2.00 seconds = 7834.26 MB/sec
Timing buffered disk reads:  492 MB in  3.01 seconds = 163.46 MB/sec

We thought this was because with no battery, read/write cache is disabled. We have bought and installed the battery backup and have used the HP bootable CD to change the cache settings to 50% read / 50% write and check cache is enabled on the drives and the controller.

Is there something I'm missing?