Why the performance decrease for an SSD when using Hyper-V

hyper-vperformancessd

I've just installed my new M4 256GB on a Windows Server 2008 R2 Hyper-V server.

On the host system using Crystal Disk Mark I've got 212 Mb/s as 4k QD32 write performance, but when I create a VHD disk on the SSD and test using the same configuration on a guest Windows Server 2008 R2, I get 7 Mb/s, i.e. about 30 times slower.

Any hint?

Of course Fixed size vhd

Best Answer

I'm currently experiencing very slow disk I/O and massive disk queues of 100+ on a guest whilst the host performance is fine. I'm not running SSDs but also Server 2008 R2 with fixed VHDs.

Not sure if this applies to you or not, but I'm investigating it as an option: http://support.microsoft.com/kb/2517329

This slideshare article also mentions offsetting your partition. I'm not sure if this is required for Server 2008 and above though. http://www.slideshare.net/Amit.Gatenyo/hyper-v-bestpractices-tipsandtricks-12756893

The article links to these pages for more info:

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