I've used Flexshare in two ways, with success.  First, I use it the way Rich does, to reduce the priority of volumes on high latency backend (in my case, SATA drives) that may otherwise create a drag on the rest of the filer.  At the time, I had a V3140 cluster with some back end SATA.  When write load was high to the volumes on those drives, I was getting a lot of cache overload with back-to-back CPs, high latency on other volumes, etc.  When I set those to low priority, this eliminated a lot of those issues.

I also used flexshare to get lower latency on a volume that was fairly unused.  Under load, the netapp won't give a lot of attention to low-use volumes, and the IO to that volume will be delayed.  This may not be preferable (in my case, this was an Oracle OCFS volume, and it was causing the oracle cluster problems by not having its writes to it serviced quickly.

Fred

From: Jack Lyons <jack1729@gmail.com>
To: toasters@teaparty.net
Sent: Wednesday, February 8, 2012 7:20 AM
Subject: FlexShare

Has anyone used FlexShare and had extremely positive results.  IT seems
that the improvement would be minor and misconfiguration could lead to
no improvement for intended volumes and degradation for others.  From
reading, it seems that you need to assign priorities to each volume
otherwise the volumes in the default queue will experience degradation.

Would anyone like to share details of how the implemented flexshare and
the impact it had on the performance issue they were working to resolve?

Would also like to know if anyone has try to 'schedule flexshare'
settings using rsh or api e.g. we want to give higher priorities to
certain volumes from 6pm to 11pm nightly.

Thanks
Jack
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