FAO Geeks - SAN and NAS Combo-ish?

[mr.anderson]

Right, I need a SAN and NAS

SAN needs to serve about 8 VM's across 2 servers - 30GB OS and 150GB Data each on average.

NAS wise, I need 5TB for backups etc.

What I was looking at was a HP MSA 2000i, putting 6 15k rpm disks at RAID 5 for the SAN and 6 10k rpm 1TB disks at RAID 5 for the NAS.

I was thinking iSCSI as its quick enough for what we need and it uses existing network infrastructure so no extra cost like with FC etc.

Anybody got any opinions of suggestions on this?

Thanks all!

[fizzwheel]

I'm not a storage expert so wont comment on your disk layout.

We dont use any NAS within our orgnisation, so all our VM's sit on SAN, make sure you have enough disk performance, I really can't stress this enough, slow disks will make your VM's run like a complete dog.

Also if you're using iSCSI, make sure your SAN / NAS is supported by Vmware, certain combo's of hardware they dont support, so you wanna make sure you have that covered off support wise.

You might want to think about having a dedicated NIC for the iSCSI in your tin as well, especially if performance is going to be an issue.

the vmware forum, is really good for asking about this kind of stuff. Have a look on www.vmware.com and go from there as I cant remember the exact URL.

Remember on iSCSI that although you don't need FC infrastructure you should really keep the SAN infrastructure seperate from your management and general data network.

I've just knocked up an 8 VM on 2 physical server layout using a Dell Equallogic 5000, windows 2008 and Hyper-V instead of VMware. Seems to perform ok through all the testing so far.

[ogden]

iSCSI's fine for what it is, I've configured a shedload of systems using it hanging off Netapp filers with no significant problems, some systems with multiple 4 to 8 node clusters hanging off them.

But if you're looking to use VMWare, I'd strongly recommend using NFS, not iSCSI. It makes life a hell of a lot simpler and with a decent storage device (haven't used an MSA, mostly dealt with EMC and Netapp) you have a lot more flexibility.

Just make sure you have enough spindles - the data capacity of disks has grown exponentially over the last 20 years but the rotational speed of the disks hasn't so it's very very easy to under-spec.
Oh, and remember RAID5 is utterly dire for random writes. If you want reasonable write performance, RAID10 will be a far better option.

Sorry, just trying out a new smiley, no offence meant

[mr.anderson]

Aww, gee, thanks.

Thanks for the comments gents.

The 8 Vm's are nothing too heavy - 4 small SQL Servers, 1 File Server, 1 Interface Server (XML), Phone system monitor server and believe it or not, a fox pro database server.

I reckon i could sacrifice the space to use raid 10, will have to see how it goes.

Ta.

[fizzwheel]

Just remember, Vmware recommend that you dont host applications that do alot of I/O on Vm's, if your SQL servers will stay small then I think you'll be OK, but if you think they're likely to grow it might be worth considering migrating them off vmware at some point in the future.

I'm a VMware/Microsoft/Citrix technical architect. I put these solutions together for customers on a daily basis.

The first decision you need to make is iSCSI or FC because as you are investing in shared storage I assume you will want to use the VMFS file system and get vMotion and DRS capability.

Are these existing physical servers which are to be P2V'd? If so have you run any capacity planning so far? If not running perfmon to get an idea of IOPS would be a good start.

To give an idea of cost difference (assuming resiliant dual path, not including disks, not including servers, as these will be the same in both solutions, but including interface cards)...

MSA2012i Dual Controller (AJ747A) RRP £4615
2 x Gigabit switches, ie: Cisco Cat 2960 (WS-C2960G-24TC-L) RRP £2345 EA
2 x Additional Server NIC's, ie: NC364T Quad Port (435508-B21) RRP £242

TOTAL £9879

MSA2212fc Redundant Starter Kit (AJ745A) RRP £6175
2 x Fibre Switches (A7984A) RRP £1735
2 x Dual Port FC HBA ie: FC2242SR (A8003A) RRP £819
4 x FC SFP (A7446B) RRP £89 (for the switches starter kit has 2 already)
6 x Fibre Cable kit (221692-B22) RRP £49

TOTAL £11933

So as you can see the FC path is not so much more expensive and will give you 4GB.

Also I wouldn't spec it myself, but if you need to save cost and you only have two hosts, you could get away with not using the fibre switches and two of the SFP's as the MSA2212fc has two fibre ports per controller and you can patch one dual port HBA port to each controller achieving redundant path without a switch.

[mr.anderson]

Thanks Fizz.

What sort of IO limit are we talking about? My sql dbs are less than 3 GBs with an average of 25 simultaneous connections.

[ogden]

Originally Posted by -Ralph-

MSA2212fc Redundant Starter Kit (AJ745A) RRP £6175
2 x Fibre Switches (A7984A) RRP £1735
2 x Dual Port FC HBA ie: FC2242SR (A8003A) RRP £819
4 x FC SFP (A7446B) RRP £89 (for the switches starter kit has 2 already)
6 x Fibre Cable kit (221692-B22) RRP £49

TOTAL £11933

So as you can see the FC path is not so much more expensive and will give you 4GB.

Not to a set of disks sharing a 3Gbps SAS bus, it won't.