Working with Dell PowerVault MD3600 SAN

Question

I've been tasked with looking at a couple of different IT projects. One of which is adding a DELL PowerVault MD3600i with 12 2TB HDDs in a RAID 5 or 6 combination. That's fine, no problems.

My query is that within the spec, the Connectivity specifies either a single or dual controller connecting to 2 or 4 servers directly. Am I right in assuming that the MD3600i is attached directly to the appropriate servers, rather than direct to our routers? Ie access is only through the attached servers, and not via a URL or equivalent? In which case, is a PHP script (for example) wants to access a file on the SAN - how does it access it? If it had a url ... ie. san.domainname.com i could understand the concept, but without that it mystifies me a little! We use Linux servers btw, with Centos or Ubutuo OS.

Can anyone tell me - or point me in the right direction web wise?

Answer 1

the MD3xxx is a DAS device, while an MD3xxxi is an iSCSI SAN. The one you specify is an iSCSI box, meaning, in short, that it uses the iSCSI protocol to provide LUNs to hosts (block and not network-FS level access). Since iSCSI uses ethernet as the media, this means the servers will be connected through direct ethernet cables to the SAN (not a good design, but possible), or through network switches (a better design, especially if you use several switches to provide redundancy and multipathing) iSCSI and DAS can be looked up in wikipedia, no point doubling that content here.

As for access, it will be direct at block level (you will see the LUNs in the MD as if they are local drives in the hosts). Management is usually through a management utility called MDSM, which can access and manage the MD device in, and out of band (through additional management ethernet ports)

For technical specs, installation manuals and more in-depth details, I suggest you get in touch with Dell. If you are not familiar with the DAS, iSCSI, SAN, LUN and ethernet concepts, I strongly suggest you get an onsite consultant, and get them to document everything they do, while explaining the process, so you can learn on the spot.

Answer 2

We've had an MD3000 for a while and they aren't bad but I wish the purchaser had bought the 3000i instead :-)

If you are going to drop some cash at Dell, you should make sure to get a small business account manager as a) you can get substantial discounts from retail and b) they can access storage specialists who will spend an hour on the phone explaining options and methods for $0.

We've been a pure Dell shop for about 4 years and I've been happy with their support.