[Gllug] Centos 5.6 3ware raid 5

John Edwards john at cornerstonelinux.co.uk
Wed Feb 8 12:49:41 UTC 2012

On Wed, Feb 08, 2012 at 12:24:47PM +0000, Ken Smith wrote:
> Hi, I didn't get any response on the Centos list so I thought I'd
> ask here for any experience with using a 3ware raid card as a simple
> IDE interface.
> I've seen comments about the poor performance of these cards with
> raid 5 configs. I have an old card with 3 x 500G IDE drives
> connected in raid 5 and I'm getting around 10mb/s write performance.
> :-(
> I'm seeing high iowait figures at times and associated very high cpu
> load average figures, probably because, under load, everything is
> stacked up waiting for the disks to actually do something.
> A non-raid sata disk in the same machine manages 70mb/s
> Does anyone know what the performance is like if I used the 3ware
> just as an IDE controller? I could then switch to software raid5?

Which 3ware controller?
Which bus (PCI 32/64bit 33/66Mhz, PCI-X, PCI-Express, etc)?
What else is using that bus?
What else could be loading CPU, RAM, I/O?
(use top, iotop, iostat, vmstat, hdparm)

I have found the 3ware 9000 series controllers to be fine in
their own RAID, individual disks, and Linux software RAID.

|    John Edwards   Email: john at cornerstonelinux.co.uk    |
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