David Hail over at the PFE Virtualization Blog notes a correlation between BIOS power state settings (c-states) and Hyper-V performance during live migrations:
How long does it take for you to do a live migration between hosts?
I ask that of all the customers I talk to that are using Hyper-V. If your answer is more than 30 seconds, then you should probably look at the settings mentioned below.
He goes on to note the performance decrease that a suboptimal power plan can produce:
[if the host or guest] is not under a heavy load, and it takes longer than 30 seconds to Live Migrate, then this blog post is for you. I have been to some customers where a Live Migration took over 3 minutes – and one of them was even closer to 10 minutes!
Sample power plan settings for HP and Dell servers are provided at the post.
If I were a [virtualized] betting man, I’d bet that general performance might be improved by these settings as well (at the cost of less-deep sleep for the processors). But I’m not, so I won’t.
Posted by Tristan Kington, MSPFE Editor
[Note to self: am I being virtualized? Note from self-Hypervisor: no]