General :: Kernel Dumps To The Wrong /var/crash?

I'm running Scientific Linux 5.5 (equivalent to CentOS 5.5), and over the past two weeks, I have had a problem with my root partition filling up, preventing anyone from logging into the server.After searching for large files, and finding none, I was mystified when du told me that the root partition had only 660 MB of disk space used, whilst df showed it full. The problem was this: the /var/crash directory had been filled up by an 8GB crash file. Now, I'm a 'proper' sysadmin and make sure that /var has its own mount point, so the crash should not have touched the root partition at all. Except it did - instead of writing to /var/crash on /dev/mapper/VolGroup00-LogVol04 which is mounted as /var, it wrote the file to /dev/md0 directly, so when all the file systems were mounted, those files were hidden under the mounted /var.