VMware’s Comparison of Storage Protocol Performance

VMware has just released a paper entitled Comparison of Storage Protocol Performance (seen at Scale the Mind and blog.scottlowe.org); maybe this will help deflate some of the too-often repeated speculation that NFS is too slow for VMware ESX.

VMware’s findings match well with what I’ve seen. On some in-house application-specific benchmarking that I’ve done, I actually saw overall better performance with an NFS datastore than with a software iSCSI datastore on the same filer. I won’t get into details, because the benchmark was specific to us (and I’d probably need a lawyer to review the EULAs before “publishing” anything…), but NFS was equal to or slightly faster than iSCSI across the board on this specific set of tests in our specific environment. Given the management and deployment advantages of NFS, that’s huge.

Of course, I wouldn’t recommend basing your whole ESX/NetApp deployment strategy off of one unsubstantiated benchmark-related post on my blog; if you’re using ESX with NetApp storage, I would strongly recommend testing NFS datastores if you haven’t already, though.



  1. Dan

    While I agree with their finding that NFS is just as good for vmware, I don’t agree with their testing methods.

    iometer tests using 100% read and write setting are not a good indicator for vmware performance. Random IO is the key.. We have NFS storage systems that are very fast at sequential IO and poor random IO and the VM’s are very slow.

    Also, 256M VM may have been an issue in the numbers…

    I believe there is a larger issue going here… I think vmware want’s to get out of the filesystem business and HPC NFS systems are their way out.

  2. Andy

    Thanks for the comment, Dan. Are you able to give more details about the configuration of your NFS systems where you saw poor performance?

    I wouldn’t be surprised if VMware wants to get out of the filesystem business, although I think they’re going to be supporting vmfs for a long time to come, given the installed base. If it is the case that VMware is looking to NFS as their way out of developing filesystems, it’s odd that we haven’t heard much of anything about NFSv4.1 from them.