One of the objectives of our recently concluded massive storage upgrade project, was to replace our vmware datastore from iSCSI to NFS. I have been hearing the advantages of using NFS versus block-level storage (ie, iSCSI or Fiber Channel), and true enough NFS did not disappoint.
We have been using iSCSI on NetApp as datastore on vmware for a long time, and it has been running pretty well. But when we perform maintenance on the NetApp storage, the virtual machines were often times affected. In addition, restore procedures can be a pain.
While Fiber Channel (FC) is still the standard storage for most vmware implementation because of its proven technology, in my experience here are the advantages of using NFS over iSCSI or FC:
1. Robust, as long as you follow the best practices guidelines. For instance, separate the NFS network from the general use network. Vmware and NetApp released white papers discussing the NFS datastore best practices. In our environment, we did several failover on the NetApp storage to upgrade the Data ONTAP version, and the virtual machines were never affected.
2. Easier to configure both on the vmware side and the NetApp side.
3. Easier to backup, via NDMP on the NetApp side.
4. Easier to restore vmdk files using the snapshots on the NetApp side, since there is no need to mount LUNs.
5. Vmware and NetApp built great tools for seamless maintenance and operations.