- You are using a XenServer machine that is running kernel somewhere around version 2.6.32
- You have a guest system like Debian Wheezy (currently testing) that is running kernel 3.0+
- While rebooting your guest system (VM) you are experiencing disk issues like I/O access, ext4 inconsistency, etc…
- The disks on guest are not mounting properly or are mounted in read-only mode or fsck has problems checking them
In the HOST logs you can see probably:
The problem is that 3.0 kernels are not using barriers anymore and there is a bug connected to that with the host kernel. If you are interested in details, check out Debian bug #637234.
The workaround is to use ‘barriers=0’ while mounting the disks in the guest system, so you correct your /etc/fstab to have: