I recently tried creating a dump of a asp.net process but it constantly failed the application pool would recycle. The process I was taking the dump of was using a couple gigabytes of memory so it took quite a while. It turns out IIS was pinging the application pool as part of the health monitoring and recycling it after 90 seconds of unresponsiveness (caused by the dump halting all execution).
So if you want to dump a large asp.net process make sure you set ping enabled to false in the application pool settings.
