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One large ~40Tb 8 x DS4243 aggr too unbalanced for 3270 ?

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fcocquyt at stanford

Nov 3, 2011, 1:11 PM

Post #1 of 4 (608 views)
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One large ~40Tb 8 x DS4243 aggr too unbalanced for 3270 ?

Fellow toasters,
we are trading up some old trays for new DS4243 trays and we are trying to decide if we allocate all 8 of our DS4243 trays to one ~40Tb aggregate (we plan to run ONTAP 8.1 for data motion) assigned to one of the cluster's heads will the advantage of all those spindles in one aggr be killed by the head being overloaded?
In which case would we be better served by 2 x 4 DS4243 AGGRs - one assigned to each 3270 head?

We also have 7 DS14-MK4 shelves to help balance out the workloads

All other things equal - I'm inclined to go for the one big 40Tb aggr vs 2 x 20Tb aggrs to reap the biggest IO capacity and performance
Currently our CPU weekly average workloads on the two 3270 heads are only 20% and 16%

My impression is a single 3270s head should be have enough headroom to push the large aggr to its full IO capacity.
But I'd be very interested to hear the advice others who have tested both options and any unforeseen issues with an aggr this large (our previous largest is 16Tb under 7.3.5.1P2)

thanks

Fletcher.

tmacmd at gmail

Nov 3, 2011, 1:23 PM

Post #2 of 4 (586 views)
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Re: One large ~40Tb 8 x DS4243 aggr too unbalanced for 3270 ? [In reply to]

I would split the load to both heads. What's the point in spending all the
money for two heads if you are only going to use one...?
4 shelves of DS4243 will perform extremely well. I saw it on my own 3170,
6070, and 6080 pairs.

I would likely create one large aggr on each head (pending the
environment...not knowing yours) and then create the volumes on that.
I would also split the DS14mk4 shelves between the heads as
well....personally, I would turn off the disk-auto-assign and assign them
myself
since the systems use software ownership, I can give a half shelf to one
head and the other half to the other head.

--tmac
Tim McCarthy
Principal Consultant

RedHat Certified Engineer
804006984323821 (RHEL4)
805007643429572 (RHEL5)

On Thu, Nov 3, 2011 at 4:11 PM, Fletcher Cocquyt <fcocquyt [at] stanford>wrote:

> Fellow toasters,
> we are trading up some old trays for new DS4243 trays and we are trying to
> decide if we allocate all 8 of our DS4243 trays to one ~40Tb aggregate (we
> plan to run ONTAP 8.1 for data motion) assigned to one of the cluster's
> heads will the advantage of all those spindles in one aggr be killed by the
> head being overloaded?
> In which case would we be better served by 2 x 4 DS4243 AGGRs - one
> assigned to each 3270 head?
>
> We also have 7 DS14-MK4 shelves to help balance out the workloads
>
> All other things equal - I'm inclined to go for the one big 40Tb aggr vs 2
> x 20Tb aggrs to reap the biggest IO capacity and performance
> Currently our CPU weekly average workloads on the two 3270 heads are only
> 20% and 16%
>
> My impression is a single 3270s head should be have enough headroom to
> push the large aggr to its full IO capacity.
> But I'd be very interested to hear the advice others who have tested both
> options and any unforeseen issues with an aggr this large (our previous
> largest is 16Tb under 7.3.5.1P2)
>
> thanks
>
> Fletcher.
>
>
>
>
> _______________________________________________
> Toasters mailing list
> Toasters [at] teaparty
> http://www.teaparty.net/mailman/listinfo/toasters
>
>

evilensky at gmail

Nov 3, 2011, 1:55 PM

Post #3 of 4 (584 views)
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Re: One large ~40Tb 8 x DS4243 aggr too unbalanced for 3270 ? [In reply to]

On Thu, Nov 3, 2011 at 3:11 PM, Fletcher Cocquyt <fcocquyt [at] stanford> wrote:
> Fellow toasters,
> we are trading up some old trays for new DS4243 trays and we are trying to
> decide if we allocate all 8 of our DS4243 trays to one ~40Tb aggregate (we
> plan to run ONTAP 8.1 for data motion) assigned to one of the cluster's
> heads will the advantage of all those spindles in one aggr be killed by the
> head being overloaded?
> In which case would we be better served by 2 x 4 DS4243 AGGRs - one
> assigned to each 3270 head?
> We also have 7 DS14-MK4 shelves to help balance out the workloads
> All other things equal - I'm inclined to go for the one big 40Tb aggr vs 2 x
> 20Tb aggrs to reap the biggest IO capacity and performance
> Currently our CPU weekly average workloads on the two 3270 heads are only
> 20% and 16%
> My impression is a single 3270s head should be have enough headroom to push
> the large aggr to its full IO capacity.
> But I'd be very interested to hear the advice others who have tested both
> options and any unforeseen issues with an aggr this large (our previous
> largest is 16Tb under 7.3.5.1P2)
> thanks
> Fletcher.

You would have double the primary size by splitting the disks among
the heads, and double the flash cache if you have that. Depending on
your IO patterns of course; our working set is easily cacheable so I
am always comfortable with more cache/less disk paradigms.

Cheers,
Eugene

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Toasters [at] teaparty
http://www.teaparty.net/mailman/listinfo/toasters

jeff.cleverley at avagotech

Nov 3, 2011, 1:58 PM

Post #4 of 4 (583 views)
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Re: One large ~40Tb 8 x DS4243 aggr too unbalanced for 3270 ? [In reply to]

Fletcher,

There are other things to consider than just CPU utilization. One
thing that comes to mind is network loading. My assumption is that
you currently use both filers for active data. Can the networking on
one handle the load for both? You will also want to monitor your
networking whenever your backup/DR processes like SnapVault run. This
spike may be too much for a single server.

It does seem a shame to have one box basically doing nothing. You
should consider future workload. It may be fine now, but what about
next year? How much trouble will that migration of data be to your
users and your backup environment?

Another thing you should consider for your disk layout is how you will
work the 32 bit to 64 bit conversion of your existing aggregates. My
understanding is the DataMotion won't work between mixed size
aggregate data. Make sure you understand the conversion process since
you may have to use some of your new disks to facilitate the change.

I've been running 40 and 70 TB aggregates on my NearStores for a
couple of years now. I haven't had any issues due to the sizes. We
haven't bothered performance testing them much since the are
NearStores running ATA/BSAS drives.

Jeff

On Thu, Nov 3, 2011 at 2:11 PM, Fletcher Cocquyt <fcocquyt [at] stanford> wrote:
> Fellow toasters,
> we are trading up some old trays for new DS4243 trays and we are trying to
> decide if we allocate all 8 of our DS4243 trays to one ~40Tb aggregate (we
> plan to run ONTAP 8.1 for data motion) assigned to one of the cluster's
> heads will the advantage of all those spindles in one aggr be killed by the
> head being overloaded?
> In which case would we be better served by 2 x 4 DS4243 AGGRs - one
> assigned to each 3270 head?
> We also have 7 DS14-MK4 shelves to help balance out the workloads
> All other things equal - I'm inclined to go for the one big 40Tb aggr vs 2 x
> 20Tb aggrs to reap the biggest IO capacity and performance
> Currently our CPU weekly average workloads on the two 3270 heads are only
> 20% and 16%
> My impression is a single 3270s head should be have enough headroom to push
> the large aggr to its full IO capacity.
> But I'd be very interested to hear the advice others who have tested both
> options and any unforeseen issues with an aggr this large (our previous
> largest is 16Tb under 7.3.5.1P2)
> thanks
> Fletcher.
>
>
>
> _______________________________________________
> Toasters mailing list
> Toasters [at] teaparty
> http://www.teaparty.net/mailman/listinfo/toasters
>
>

--
Jeff Cleverley
Unix Systems Administrator
4380 Ziegler Road
Fort Collins, Colorado 80525
970-288-4611

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Toasters mailing list
Toasters [at] teaparty
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