Hardware Thread, SAN advice in Technical; Hi Guys,
I'm looking at getting a SAN but how do I know which is the correct/best SAN for me. ...
13th May 2011, 12:15 PM #1
I'm looking at getting a SAN but how do I know which is the correct/best SAN for me. It primary use will be to run my VMWare servers which I currently have running on the local HHDs of the server. I also want to use it via ISCSI I would imagine for the main file store for the school.
I have various quotes etc so far from CORAID, HP and Overland but I don't 100% know what I'm looking at, what the features I should be looking out for or what the management software is like on the SANs.
I know I need a SAN supports ISCSI unless I should be using another technology to connect to the san. Make sure it supports the various lvls of RAID? (But which should I use). The physical drives/power modules and network interfaces are hot swappable and redundant and that the network cards upgradable from 1GB to 10GB in the future also probably want 16TB in total – 8 usable
Is there anything else I should be asking? Does anyone have any recommendations?
13th May 2011, 12:28 PM #2
we decided what our budget would be and what types of disks we wanted and how much storage and took it from there.
we ended up with the Hitachi san with a mixture of SAS and 15000k SATA, connected via Fiber Channel rather than iSCSI
Thanks to RabbieBurns from:
13th May 2011, 12:51 PM #3
I still can't quite figure out why everyone is so obsessed with having their disk storage loosly coupled to their VM instances as if you're all running Amazon-scale datacentres, but if you're going to buy a SAN then the QNAP devices seem to be good value for money. Ours seems to be coping with being both an iSCISI target for Xen Server VMs and an SMB file server - you can at least save one lot of network traffic by having SMB traffic go straight to your storage server, rather than to a VM acting as a file server and from there to the storage server over iSCISI.
Originally Posted by FatBoy
2 Thanks to dhicks:
FatBoy (13th May 2011), zag (19th May 2011)
13th May 2011, 01:44 PM #4
What kind of budget are you looking at? You're asking for some fairly high-end features there (10GbE, 16TB) so this won't be extremely cheap if you want to do it properly.
NetApp, EMC, HP, and to some extent Dell are worth a look. My money goes to Oracle Sun S7000 though. iSCSI/NFS/CIFS all licensed for free, scales anywhere from 12TB up to several PB. 10GbE available and will take plenty of NICs. Network interfaces generally are never hot swappable - however you wire up your networking so they're redundant. The disks are SATA for capacity and Flash/SSD accelerated for performance, you can add however many you need based on your IOPS requirements.
I've got an older S7410 with 22TB raw in RAID-DP with read/write SSDs serving up a couple of TB of data directly to Windows users over CIFS and running all my virtual machines over NFS or iSCSI.
41 page thread on the (now older) S7x10 suff (it's up to S7x20 now) HERE.
PM me if you want more details or supplier to contact.
Last edited by Duke; 13th May 2011 at 01:49 PM.
13th May 2011, 02:11 PM #5
What does that mean? you planning on just mirroring say 4 x 2TB on to 4 x 2TB drives?
13th May 2011, 02:27 PM #6
I guess either a) Needs 8TB now but will scale to 16TB later, or b) 16TB works out to 8TB usable space.
Originally Posted by plexer
If the latter, my S7410's 22TB raw works out about 14TB usable after hotspares, RAID6 and formatting. My 6TB raw on the NetApp gives about 4TB usable.
If the former, I would now only EVER buy storage that's expandable - ideally silently without having to destroy any storage pools or backup and restore my data. I've been bitten too many times by "oh, 20GB will be enough" ... "oh, 2TB will be enough" ... "oh, 6TB will be enough". I want to be able to plug in another disk tray as required and carry on working.
13th May 2011, 02:29 PM #7
Not sure whether we are mirroring yet or not tbh and that was only a rough estimate, is mirroring over kill for a small school? I was thinking of just a RAID 5 or 6 setup or even 1. what's the general consensus on which RAID level you should use when it comes to speed?
13th May 2011, 02:32 PM #8
we have a whole bunch of different raid groups within our SAN depending on the type of disks and the purpose of the storage
13th May 2011, 02:44 PM #9
+1 on that.
Originally Posted by RabbieBurns
For performance with some redundancy I guess you want RAID 10. When you say mirroring do you mean RAID 1 or do you mean two completely separate devices? The latter is nice, but only if your SLA requires it and your budgets can meet it.
RAID 6 with SSDs/Flash seems to be working well for me, even for virtual machines. If I bought another disk tray or reconfigured my storage pool I might put some stuff on RAID 10 for performance.
EDIT: RAID type should really be determined by your calculated IOPS requirements, then working out what your SAN would provide based on disk types/interfaces, spindles, then what RAID level you need. If you want RAID 5 for example, you may need to purchased larger quantities of faster disks to meet your requirements compared to what you might need if you went RAID 1.
Last edited by Duke; 13th May 2011 at 02:47 PM.
13th May 2011, 03:17 PM #10
@Duke how much SSD storage do you have by the way.. im jealous already ;p
13th May 2011, 03:26 PM #11
Originally Posted by RabbieBurns
The Flash is purely used for acceleration and you don't get to choose what you put on there. The underlying OS works out what should be cached in there and the RAM (16GB RAM on mine, I think the minimum on the newer models is 24GB or 32GB) to give the best performance. Mine has got a 100GB read SSD in the head and two 18GB log SSDs in the disk tray.
For those wondering prices, I can only give ballparks of my own experience:
We needed to expand our storage to meet growing user requirements and our need for centralised VM storage. We already had a NetApp box so they quoted to expand our solution to meet new requirements and came in at £120,000. Sun (via Cutter Project) came in with a larger and faster solution in the S7410 for £37,500.
In the new 7x20 models, 12TB would start at around £17k list, but be considerably less after educational discounts (PM me if you need to know who to talk to in order to get these prices). 24TB should be under £20,000 after everything has been included. Bear in mind these prices include all protocols and all OS/firmware upgrades forever. You're not going to suddenly get hit with a £10,000 bill if you need to add an NFS licence, unlike some providers.
13th May 2011, 03:29 PM #12
Thats for the storage only? I take it you already had the VM Host servers?
13th May 2011, 03:31 PM #13
Yep, that's purely storage, virtualisation ended up being a completely separate project.
Originally Posted by RabbieBurns
13th May 2011, 03:51 PM #14
I'm currently running an MSA 2000 Fiber channel san with dual controllers and an HP fiber switch and it hangs off the back of 3 HP dl380's with 64gb in 2 and 16gb in the other
But as others have mentioed something that is expandable is needed.
I'm just getting quotes in for the HP Storage Enclosure bolt on which will double the amount of storage we have.
They currently have 12 x 450gb 15k Sas drives in.
17th May 2011, 10:54 AM #15
I have been quoted for a Coraid SRX2800-G SAN
Six 1GigE Ports
36 disk bays for 3.5" SATA, SAS or SSD drives
with 16 coraid 1TB 7.2 SATA HDDs installed
with 3 years support + maintenance
for about £12,000
The AoE (ATA over Ethernet) protocol the Coraid SAN uses looks impressive compared to iSCSI or Fibre channel.
Does anyone have an opinion on Coraid stuff or what I posted above?
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