XIV and Round Robin

[esnmb]

IBM recommends using round robin for the XIV per best practice, which we have set already since all paths are active/active.  I am reading over more documentation now and saw an interesting piece.  By default, at least in ESX 4.x, round robin will use another path after every 1000 I/Ops, but lowering this to their recommended 10(!) should have a drastic improvement  for latency, MBps and I/Ops. 

They give a handy little script that will loop through all XIV paths and make this change.  Of course I would need to run it on every hosts, and then again after adding another volume. I am thinking this can be better accomplished via the vMA to run the script against al hosts simultaniously or something...

But what are your thoughts on this change?  No one from IBM ever mentioned this to me so this is quite new.  We have a Gen 2 and two Gen 3 XIV's now with a couple more on the way...

[a_p_]

There's an interesting blog post at http://www.yellow-bricks.com/2010/03/30/whats-the-point-of-setting-iops1/ about changing the IOPS. Don't miss to read the comments!

André

[esnmb]

Excellent, thanks!

[mcowger]

It might be better just to change your claim rules, so that the proper path selection policy gets automtically selected for new devices.

[TomHowarth]

Exactly and then you just need to manage the exceptions like RDM's attached to MSCS hosts rather than every thing.