Erratic performance on Windows 2008 R2 Hyper-V

[chuckk281]

Nick was looking for some help on a Hyper-V question:

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I have a customer deploying Windows 2008 R2 Hyper-V on BL465 G8 with Emulex 554FLB CNAs.

We are seeing largely differing levels of performance in the GUI while we are configuring the Hyper-V host itself, but there doesn’t appear to be any consistent thread. For instance, we launched the AV install on 2 separate servers and on one it run almost immediately but on the other it took substantially longer to open (AV is just the example, it has been seen on different tasks such as NIC teaming and Windows update). When it hangs or runs slow there don’t appear to be any high CPU time processes.

Each host has 32 cores and 128GB of memory and is boot from san (3PAR)

I saw a similar issue with VMware ESXi VM and it proved to be a driver issue (the driver is configured for a heavy load and only running 1 VM caused poor IO performance on the fabric). Unfortunately I cannot find anything similar for Hyper-V.

Has anyone else experienced anything similar?

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An update from Nick:

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A quick update, we appear to (hopefully) have fixed this now, we are BFS and running everything at 8GB, but the portfill was set to 0. We have changed this to 3 and so far performance appears to have stabilised.

Interestingly a few of the SAN consultants I spoke to believe this should have been the default for brand new switches (as did I) but it was not the case in our switches.

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Any other input for Nick?