I was recently migrated from UML to Xen and since then, I have been getting I/O rate threshold e-mails that indicate about a 15x increase in I/O. It's not log rotation. Has anyone else seen this?

What's your current average IO? It might be that your threshold is too low.

I had the threshold set at 250 and would rarely get alerts above that. Now I get alerts that it is around 1600. This may or may not be a concern, but it is directly related to the migration.

I forget the exact details (it has been awhile), but UML and Xen do use different units for I/O measurement. I want to say UML used operations/second while Xen uses bytes/second, but don't quote me on that. A factor of 10 difference is typical.

IIRC, newly deployed Xen linodes these days have the I/O threshold set to 2000 by default. So according to Xen standards, 1600 might be just fine. Just a guess.