[Beowulf] LVM performance problems

[Judd Tracy]

That seemed to work just fine, it now averages ~205MB/s read thanks.

Judd

Bernd Schubert wrote:
> On Friday 04 May 2007 15:40:37 Judd Tracy wrote:
>   
>> I am trying to bring up a small file server and am noticing some serious
>> performance issues when using LVM.  I created a software raid /dev/md0
>> which I can read at ~195MB/s using the raw raid device, but as soon as I
>> put LVM on top of it the read speeds drop to ~95MB/s using a raw lvm
>> partition without a filesystem.  When I use and xfs filesystem on top of
>> the lvm partition it drops down to ~40MB/s.  This seems like a
>> processing power issue, but the machine is a dual processor opteron
>> system with 4GB of ram in it.  Does anyone have some insight into why I
>> might be having such problems with the system.
>>     
>
>
> try something like this: 
> blockdev --setra 8192 /dev/{volumegroup}/{logical_volume}
>
> You should also try smaller and larger numbers.
>
> Hope it helps,
> Bernd
>
>