This is one of those week or so long learning experiences that you must go through whenever exploring a new technology.
I installed Centos 5.3 and Xen on a hot new piece of hardware with the intention of runnig paravirtualized Centos 5.3 images on it. I’d probably be running a half dozen images at a time and with disk images at > 4GB I thought I’d run XFS as the Dom0 file system to speed the file access/create/delete times.
Every time I’d run a DomU guest, the host/Dom0 machine would consistently, but at different time intervals, crash. That’s right, the entire server would crash/hang/freeze. After a week of goofing around I finally tried a guest on a stock ext3 file system and Shazam! everything worked.