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Re: [Xen-users] Xen and I/O Intensive Loads

On Thu, 2009-08-27 at 08:25 -0600, Nick Couchman wrote:
> Let's see...the SAN has two controllers with a 4GB cache in each
> controller.  Each controller has a single 4 x 2Gb FC controller.  Two
> of those ports go to the switch; the other two create redundant loops
> with the disk array (going from the controller to one disk array, then
> to the next disk array, then to the second controler).  The disks are
> FCATA disks, there are 30 active disks (with 2 hot-spares).  The SAN
> does RAIDs across the disks on a per-volume basis, and my e-mail
> volume is using a RAID10 configuration.

FCATA?  Well, that isn't going to help your situation any.  But 30
spindles is a good start.  How many are in your particular RAID 10
group?  It's sounding like 1500 iops might be all this guy can handle
(ATA, maybe 120 iops, RAID 10, so you're using at most 14 of those
disks, that'd give you 1680 iops max -- for reads -- half that for

> tuning parameters for the elevators.  I haven't got around to trying
> something other than XFS, yet - it's going to take a while to sync
> over stuff from the existing FS to an EXT3 or something similar.  I'm
> also contacting the SAN vendor to get their help in the situation.

Shut down, rsync, remount, start up.  I don't think your SAN vendor
could really help here...?


John Madden
Sr UNIX Systems Engineer
Ivy Tech Community College of Indiana

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