[CentOS] Poor RAID performance new Xeon server?

John R Pierce pierce at hogranch.com
Sat Jan 10 23:29:11 UTC 2009


Stewart Williams wrote:
> I have just purchased an HP ProLiant HP ML110 G5 server and install ed 
> CentOS 5.2 x86_64 on it.
>
> It has the following spec:
>
> Intel(R) Xeon(R) CPU 3065  @ 2.33GHz
> 4GB ECC memory
> 4 x 250GB SATA hard disks running at 1.5GB/s
>
> Onboard RAID controller is enabled but at the moment I have used mdadm 
> to configure the array.
>
> RAID bus controller: Intel Corporation 82801 SATA RAID Controller
>

that is essentially desktop grade disk IO


> For a simple striped array I ran:
>
> # mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/sdb1 /dev/sdc1
> # mke2fs -j /dev/md0
> # mount -t ext3 /dev/md0 /mnt
>
> Attached are the results of 2 bonnie++ tests I made to test the 
> performance:
>
> # bonnie++ -s 256m -d /mnt -u 0 -r 0
>
> and
>
> # bonnie++ -s 1g -d /mnt -u 0 -r 0
>
> I also tried 3 of the drives in a RAID 5 setup with gave similar results.
>
> Is it me or are the results poor?
>
> Is this the best I can expect from the hardware or is something wrong?
>
> I would appreciate any advice or possible tweaks I can make to the 
> system to make the performance better.
>
> The block I/O is the thing that concerns me as mostly I am serving a 
> 650MB file via samba to 5 clients and I think this is where I need the 
> speed.

is this a sequential or random access application thats using this 
file?   is it read only/mostly, or is it random update?


its rather hard to read your bonnie output logs as they aren't very 
columnar. but it appears the sequetial read speed at least is really high.

i'm seeing 55MB/sec random(block) and 1.4GB/sec sequential reads on the 
1GB file, so I dunno what your issues are...   of course, a 1GB file 
sits entirely in the system cache assuming a reasonable amount of 
otherwise idle memory


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