In addition, NFS-exported volumes are more easily managed as a whole. If you need to adjust files on an NFS volume, you mount it from a workstation or even from a VM that's running off that volume, and go to town. You can back up an entire NFS volume from a Linux box with only a few commands. You don't need to worry about stepping on any toes while doing so. But if you inadvertently mount an iSCSI LUN on the wrong machine due to a presentation error, all could be lost.
In many cases, you might find that NFS performance beats iSCSI. Depending on the transport and the storage in use, NFS throughput can exceed iSCSI for some workloads, especially when there are a high number of writes. At worst, NFS usually performs on par with iSCSI. In terms of VMware's VAAI (vStorage APIs for Array Integration) and the like, iSCSI has a more advanced set of tools, but some storage vendors support VAAI on NFS for some primitives, such as full copy and clone offload.
NFS versus Fibre Channel is a different discussion, given the fact that Fibre Channel requires dedicated HBAs and switching, but even against FCoE (Fibre Channel over Ethernet), NFS wins hands-down in terms of simplicity. As far as resiliency goes, redundant storage paths for iSCSI and Fibre Channel or FCoE are more advanced than NFS, as most hypervisors will allow for multiple concurrent paths to storage, while NFS is limited to failover or bonded NIC teaming. In practice, however, this is usually not a significant problem. Also, it's hoped that widespread NFSv4 adoption will bring about multipathing and additional security features.
For a few years there, iSCSI was the darling of the virtualization world -- at least for those not requiring the then-faster speeds of Fibre Channel. But the worm seems to be turning now, and NFS is pushing back into the limelight, just as you might expect for an immortal technology.
This story, "Old NFS is the new darling in virtualization," was originally published at InfoWorld.com. Read more of Paul Venezia's The Deep End blog at InfoWorld.com. For the latest business technology news, follow InfoWorld.com on Twitter.