Just a doubt about VMware on NFS stability.

NFS strage by default have NFS locks enabled: this permits best protection and avoids more than one access at time on a vmdk file.

During a vMotion, a backup or a snapshot (VMware one), with NFS locks enabled, the ESX o.s. creates some freeze extended in time, sometimes also dozens of seconds. These limits have been improved with ESX 3.5U3 but not completely solved.

 

To avoid these strange problems we need to disable NFS locks. But in this case the issue (I’ve already experienced it a couple of time) is that if VMware cluster fails or malfunctions while it’s in maintenance mode there’s the risk that the VM will run on two different hosts at the same time: the result is a BSOD on that VM and that VM file system (vmdk) will be definitively corrupt!!!

 

Wth NFS is true that we can have good performances, high flexibility but we can’t use VCB, storage vMotion, linked clone and VDI. There aren’t SCSI reservations as VMFS has, so it’s less stable.

 

Regards,

 

 

 

 

Running ESX over NFS is (imo) the way to go. I moved from FC to NFS about 2 years ago (2.5.4) and have never looked back. Being able to restore crash consistent out of the box and the extra flexibility of being able to access your VMDK files directly instead of through VMFS is very nice. We’re currently running 300 VMs on 5 IBM 3850m2s with dual 1 gig connections to our switches and then dual 10g to the filer itself. Most of my VMs are on SATA with the higher IO boxes on 15k FC disks. Dedup is also very nice, just realize that the first time you run the SIS job (the dedup process) it will hammer your disks since it has to look at every block with data on it.

 

If you’re hard set on block based storage then I don’t think the Netapp boxes are worth it, but I really think NFS is the way to go. Having the extra layer of abstraction may be a bit less efficient, but the extra flexibility and related uptime is very much worth it.

 

 

I am after opinions / Pros and Cons on running a substantial VMware infrastructure of approximate 200+ VMs using the 2 mentioned storage systems.

 

Obvious benefits of the NetApp seem to be around the De-Dupe out of the box. Any other thoughts / experiences would be appreciated

 

Fibre attached Dell R900s will be running the ESX side of things.

 

Paul McGuinness

Infrastructure Services Manager

FINEOS Corporation
ENTERPRISE SOLUTIONS for INSURANCE, BANCASSURANCE AND SOCIAL INSURANCE

 

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