I have an environment with servers (5-6) virtualized and hosted locally on the hypervisor. They act as file servers, so am thinking of moving the files out to a NAS (TheCUS or QNAP) and share over iSCSI or NFS.

Both the vendors are "vmware" certified and can do iSCSI, but I am concern about the performance given that the server is virtualized, and the NAS is 2GB ram only (e.g. QNAP 809U-RP).

or should I stick to NFS? which is file based sharing...


I'd stick to NFS but not because of anything you've said.

In general iSCSI performance inside VMs is ok, certainly no enormous drop in IO rates but what does worry me is how you'd manage the clustered file system you'd be creating by mounting these iSCSI block-level disks inside two or more VMs. You don't mention your VM OS but few file systems that ship natively with ANY OS are cluster-aware, meaning almost instant data corruption. If you do choose to go down that route then for Windows I'd recommend using either Veritas Storage Foundation or Microsoft's own Cluster Services; for Linux I like Oracle's OCFS2 - either way don't use raw-NTFS or ext2/3/4.

So to conclude I think you'll have less complexity and therefore better supportability just using NFS.

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  • My concern would be performance, for NFS. For iSCSI, in this particular scenario, it would definitely be 1 iSCSI LUN to one VM, thats for sure. If that is assured, will you suggest iSCSI then? Thanks :) – DarenTay Jul 5 '10 at 4:29
  • I think either would be fine and although one would perform better than the other I wouldn't like to guess which of iSCSI or NFS it would be without knowing a lot more about your setup - either way there shouldn't be that much difference in speed. – Chopper3 Jul 5 '10 at 6:34
  • I see :) Well, thanks for the input :) – DarenTay Jul 6 '10 at 2:14

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