[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Condor-users] tuning a file server

On Tue, 2005-08-02 at 12:44 +0200, Steffen Grunewald wrote:

> > The 2.6 IO schedulers tend to _better_ than the 2.4 one.  The default is 
> > to use the 'anticipatory' scheduler which tends to be excellent for most 
> > needs.
> I suppose it's anticipating the wrong stuff. If 100+ client tasks start
> to send off 24 nfsd threads to work, probably the scheduler gets a bit
> confused. I guess that some elevator type would be the better choice?
> (Can you point me to some docs?)


Aha! The latter has some relavant comments that I wasn't aware of:

"Attention! Database servers, especially those using "TCQ" disks should
investigate performance with the 'deadline' IO scheduler. Any system
with high disk performance requirements should do so, in fact."


"Also, users with hardware RAID controllers, doing striping, may find
highly variable performance results with using the as-iosched. The
as-iosched anticipatory implementation is based on the notion that a
disk device has only one physical seeking head.  A striped RAID
controller actually has a head for each physical device in the logical
RAID device."

David McBride <dwm@xxxxxxxxxxxx>
Department of Computing, Imperial College, London

Attachment: signature.asc
Description: This is a digitally signed message part