VM Performance iSCI / Fibre vs NFS

[RParker]

According to recent reports, NFS is a better solution for hosting VM's. I am not so sure, after reading this thread:

So since so many people have tested VM benchmarks on their SAN, I was curious to see if someone took those same VM's and moved them to NFS to see if there was indeed a significant difference in performance? I believe the difference in performance over NFS is due to comparing from LOCAL storage to NFS, not from Fibre/iSCSI to NFS.

I would really like to know if someone can confirm or deny that NFS is better than the other leading technologies, using their SAME VM's today. Thanks.

[RParker]

Guess no one has done this yet.

[azn2kew]

With a single VM and/or connection, iSCSI outperforms NFS anywhere from 10-50%. However, as the number of VMs per server increase, NFS gradually catches up then exceeds iSCSI performance at about 15 virtual machines per server. There are a few reasons, mainly in how NFS locks files compared to iSCSI and also that from the client-side of things, NFS uses much less CPU than iSCSI.

There are other advantages of NFS as well - by default VMDK files on NFS are formatted as sparse volumes allowing for thin provisioning. Also, being normal file shares, they are much easier to manage and backup.

Regards,

Stefan Nguyen

"The Power of Knowledge"

[RParker]

Well maybe true for iSCSI, our San Admins had us believing it was faster than Fibre, but Netapp and VM Ware confirmed that it is not. That's what I was curious about. We won't be using iSCSI anyway, but thanks for your input.

[azn2kew]

Are you really need to get this info otherwise I can call my friends working for EMC as Storage Engineer can give some thoughts. I'll post it when I talk to him tonight!

Regards,

Stefan Nguyen

"The Power of Knowledge"

[BigHug]

We did some benchmarks on NFS, iSCSI and FC datastores on the same array. For squential io, FC is much better since we have 2GB FC san. iSCSI hba is a bit better than NFS. For random io, all 3 are no different. Also ESX SW iSCSI is very slow. maybe 30 or 40% slower.

BTW, different arrays will probably give you different results. We tested on Netapp and Netapp's NFS is really good. If you try on EMC, you will probably get a different result since EMC's nas is not as good as their block storage. But that is jus my experience on the old EMC.