I have been looking for a good answer to what seems like a simple question.
Our organization recently decided to expand our virtualization to include desktops, so we purchased an NX4 for the storage. We have been running vSphere 4 was DAS and a Netgear readynas using iSCSI. All was fine just limited flexibility and capacity.
The NX4 supports both NFS and iSCSI, but which is the best solution. VMWare recommended iSCSI, but at the same time said to speak to EMC. I searched the forums, with no great answer to swing me either way. We are purely a windows house, so have no need for NAS other than the VM servers. We have 1 server, now, but will probably have 4 hosts running 200 desktops by next year.
I started setting the celerra up with NFS, a recent issue I had with the ESX server (resulting in a reinstall) required me to move the data off the server, and NFS was my only option, so it seemed a logical choice for the future, plus EMC's Celerra plug-in works for NFS, and less features on iSCSI.
Am I missing a feature of iSCSI that would make me lean towards it? The only limitation that I have with my NFS setup now, is I need to expand the FS beyond the maximum volume size, I dont see a way to add more physical storage to the NFS, for example it is RAID 5 + 1 now, near maxed, but I can create another 5 + 1, just cant add to the filesystem. I want to maximize space on Celerra and no over allocate as we only plan 61 deskops and maybe 10 servers.
I already reviewed that doc and post. I guess I am in much the same boat. There does not seem be a clear answer of which is the best choice, only preferences based on enviroment and personal requirements. I have not found a single issue with using either, but that may change as I add more VM's. What I am looking for is best performance and data protection. I even read a white paper that compared FC, iSCSI, and NFS. FC was a clear winner but the other two were neck and neck.
Does anyone have real world experience that would make them use iSCSI over NFS?
My 2 cents
NFS is fine – just make sure you have a recent DART release and use the uncached mount option (the vSphere NFS plugin sets that automatically)
In terms of expanding a datastore its easy with NFS – just extend the file system (NOT the raidgroup).
The one functionality I can think of that’s not possible with NFS (vs. ISCSI) is RDM