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I was looking at Dell Equalogic devices, the PS4100E. It says you can have two PS4100 boxes for 36TB each. Am I reading that right? What if I want to have more space? Can I span to more 4100E devices or do I have to have another set of boxes, another set of IP address?

Is there anything I can do to make it so I have a switch and one IP address for an entire "never ending" set of disk arrays?

I'd like one ip address (iscsi) for unending space. Is that possible?

Thanks.

johnny
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4 Answers4

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I was looking at Dell Equalogic devices, the PS4100E. It says you can have two PS4100 boxes for 36TB each. Am I reading that right? What if I want to have more space? Can I span to more 4100E devices or do I have to have another set of boxes, another set of IP address?

No, you're not reading that right, you can have groups of two - that's it, no more, if you want more space you need to buy something else.

Is there anything I can do to make it so I have a switch and one IP address for an entire "never ending" set of disk arrays?

Yes, but not like that, maybe not 'never ending' either, but there's lots of solutions like that (Gluster etc, basically google for 'distributed filesystem'), just not this Dell thing.

I'd like one ip address (iscsi) for unending space. Is that possible?

Yes, as above.

Chopper3
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  • I was kind of hoping it was something I could pay for though, to get support. – johnny Jan 21 '13 at 15:49
  • Speak to a proper storage vendor (i.e. not Dell), they'll sell you something just like it and support it. HP's do their Ibrix and Lefthand stuff that scales and performs well, not free though. – Chopper3 Jan 21 '13 at 16:19
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    Here's how to pay for Gluster : http://www.redhat.com/products/storage-server/ – mfinni Jan 21 '13 at 16:23
  • @mfinni - well remembered, I'd forgotten about that – Chopper3 Jan 21 '13 at 16:25
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"unending space"... you're funny.

The PS4100 has twelve drive slots and at this time you can order them with 3TB disks. This of course adds up to 36TB.

That's before implementation of course. With that large a capacity drive, running anything other than RAID10 will be suicide on rebuild times so... you lose TWO disks to hot spares, and two more to RAID. You lose some disk space to formatting.

So what's the math then? 5 x 2.72TB = 13.6TB that you can use to create LUNs and extend them to servers. Those servers will in turn still need to manage those volumes. If you ran RAID6 you'd get 21TB.

There will be at a minimum three IP addresses used by your array if you cable it properly. The group IP (used to discovery of LUNs) and each active interface (usually two on a PS4XXX series). When you add another shelf, it will consume two more IP addresses, but it should load balance the data across the two shelves as long as the disk types are the same and they are placed into the same storage pool.

So... two PS4100 shelves would net you 42TB of space you can allocate to servers via iSCSI. Note, there is a maximum of two 4XXX series devices per group, and groups are used to manage and pool disks together.

cyberhicham
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SpacemanSpiff
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  • Corrected my math... RAID10 will net you 13.6TB, RAID6 does a little better on storage. Remember these are SATA disks.... please answer my question above on what your use case is. If this is all file storage, you may be better suited with NAS devices. – SpacemanSpiff Jan 21 '13 at 16:17
  • All file storage. What else can I do with them? Sorry. I thought they were only for files storage. – johnny Jan 21 '13 at 18:21
  • No, the Equallogic solution is for providing block storage over iSCSI to a server. I think based on the limited information you've provided, a server with a bunch of hard disks in it with the ability to add disk shelves will be a more ideal solution. You can run the OS of your choice, or something like OpenFiler to provide file services. – SpacemanSpiff Jan 21 '13 at 21:34
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@Johnny

Its true that you can only have 2 PS4100 boxes in a group, but there is no reason why you can't add PS6100s after that. Its a Dell EQL licensing thing no more than 2 4100s in a group, after that, you need to add PS6100s. The idea here is that after 2 PS4100s, you are definitely beyond entry and headed toward enterprise.

Dave M
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Jason Runnion
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Or you could save money and put 2 of these together

http://blog.backblaze.com/2013/02/20/180tb-of-good-vibrations-storage-pod-3-0/

BugMagnet
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  • Nope, wrong solution to the question. http://blog.backblaze.com/2009/09/01/petabytes-on-a-budget-how-to-build-cheap-cloud-storage/ "One of the most important concepts here is that to store or retrieve data with a Backblaze Storage Pod, it is always through HTTPS. There is no iSCSI, no NFS, no SQL, no Fibre Channel." – mfinni Feb 26 '13 at 20:10
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    -1 Wrong solution, plus there's bugger all in the way of support, so you're screwed when it breaks and loses all your data. Good for Backblaze, sucks for anyone else, really. – Tom O'Connor Feb 26 '13 at 20:31