How dynamic is your environment? It is very simple to add shelves in the future as your load requirements increase. It is a bit more complex, and costly, to do a controller upgrade. A few things to consider.
Controller: The FAS3250 represents the current generation of NetApp controllers, and if you aren't considering Clustered Data OnTap, you should be. The 3240 can only participate in a cluster with 4 or fewer nodes. The 3250 can go to 8 nodes (62xx series can do 24). There are other improvements you get in a 3250, but essentially you are buying a previous generation to save $ with the 3240.
Shelves and Drives: NetApp disk shelves (DS2246, DS4243, and DS4246) all have 24 drives. Your config uses multiples of 20 making me question how. You are also comparing 600gb to 900gb drives SAS drives, not just 10k 2.5" vs 15k 3.5" drives. That's 2 factors slowing you down.
You can buy 600, 900, and now 1200 gb SAS 2.5" 10k RPM disks. These all have similar performance profiles, but as spindle size increases your iops / GB drop. You also should compare prices on these shelves and see that the larger sizes cost more per GB than the smaller ones.
Note that NetApp has EOA'd (End of Availability) the DS4243 shelves with SAS 3.5" 15k drives. Buying these now means that your next disk purchase will end up being different hardware. You do get more IOPS from the 15k drives, but you pay in power, space, and buying hardware that's no longer being sold by NetApp.
I suspect that if you have this re-quoted to have the 3240 to 3250 comparison with the same drive and shelf type (I'd go with the DS2246 600gb drives but you can look at the 900s on both too) you'll see less spread in price and your choice will be easier.
Finally a question for you. Why would you buy IBM rebranded filers and not NetApp? I am curious as to what the IBM value add is in the equation?
Colin Bieberstein
On 2013-09-13, at 1:36 PM, Blake Golliher <@gmail.com> wrote:
I'm usually in the camp of more spindles is better then not enough. Spindles tend to dictate performance more then the controller does, in most cases, but not all.
Typed with my thumbs!
On Sep 13, 2013, at 12:28 PM, Ray Van Dolson rvandolson@esri.com wrote:
Hi all;
Am trying to understand what sort of performance difference I might see between two different configurations:
- IBM N6240 E21 (FAS3240C) w/ 120x600GB 15K 3.5" SAS and 512GB of
flash cache 2) IBM N6250 E26 w/ 80x900GB 10K 2.5" SAS and 512GB of flash cache.
Sorry, on the latter I don't know the equivalent FAS. Probably FAS3250C?
We have fewer spindles, but newer, beefier controllers.
Our workload is primarily VMware via NFS. Lotsa random reads and writes (more on the read side) with I'd say the bulk of the IO requests in the 64KB+ range.
Will I regret going with fewer spindles?
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