Since you haven't gotten much response, and you did ask for ANY insight,
I will offer mine! Be forewarned, I haven't used NetApp for TSM disk
pools, but on paper it would seem like a good fit. NetApp / WAFL
coalesces current write activity and spits the data out as full stripes
to the underlying array.  By writing a full stripe at a clip, it
eliminates the need to perform any reads for RAID parity calculation (as
its replacing the stripe in its entirety, it can calculate the proper
parity with the data in hand). As such, your random-access disk pool
almost turns into one big multiplexed sequential file.  Assuming low
restore / migration activity during your backup window, I'd expect you'd
see very good write throughput, as very little head movement would be
required (provided you have sufficient free space available in your
aggregates so it doesn't have to hunt for free stripes).

I'm not sure how TSM determines the order of objects to transfer in the
event of restores and migrations from disk pools - if they are selected
in the order written the reads should have good locality to them.
Depending upon how many concurrent write streams there were at time of
backup, you may end up skipping over a fair amount of data, but
presumably not hunting too far for that next stripe.  On the other hand,
if TSM calls for the objects in some non-temporal order, you're going to
be hop-scotching all over and throughput will drop.

I, too, would be interested in what others have to say, either from
real-world experience or theoretical musings.
-Ken

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Mayhew, James
Sent: Monday, August 27, 2012 4:28 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: NetApp for Primary Disk Pool


BUMP... Does anyone have thoughts on this?

From: Mayhew, James 
Sent: Thursday, August 23, 2012 6:42 PM
To: 'ADSM-L AT vm.marist DOT edu'
Subject: NetApp for Primary Disk Pool

Hello All,

We are considering using a NetApp V6210 with some attached shelves as a
block storage TSM primary disk pool. Do any of you have any experience
using NetApp storage as a TSM primary disk pool? If so, how was your
experience with this solution? Did you have any performance issues? How
was it with sequential workloads? Any insight that you all can provide
is greatly appreciated.

Best Regards,

James Mayhew
Storage Engineer
HealthPlan Services
E-mail: jmayhew AT healthplan DOT com


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