With ESX 5.1U1, I’m observing slow I/O performance from VMs on NFS database exported from NAS Storage system. With 512KB Sequential Write workload within the VM on a NFS Datastore provides approximately 50MB/s data transfer rate.
I made an interesting observation – VM on a Local Datastore provides higher data transfer rate( > 350 MB/s ) and continues to provide the high throughput even after migrating it to NFS datastore and hits the limit of NIC(In my case NIC is 1Gbps, i.e close to 128MB/s). I stopped the workload and re-triggered, still it I get same throughput(close to 128MB/s). But if I restart the VM, then re-triggered same workload, but throughput does not go beyond 50MB/s.
What gets lost when a VM is restarted, and starts performing slow
Based on this discussion, I tried with ESX50.U1, and also configured ESX as per the “Best practices for running VMWare vSphere on network-attached storage” , but performance is the same
Regards
Susanta