If you have a software raid /dev/md0, even if you sub-partition it, you cant use those for openfiler, software raids can't be partitioned(and work).
Also, if you rebuild your openfiler, and for some reason your disks are now type "gpt" you may not be able to add them to a raid, use these commands
do that for each of your drives to get them back to msdos type so you can re-raid them. Also be VERY CAREFUL with that command as it will nuke/wipe any drive you use it on, and by default if you don't specify the 'parted' drive, it defaults to your first/boot drive..and blamo, your back with a CD reinstalling the OS...not that I know...from experience....
To Zero out a partition, here is the command
dd if=/dev/zero of=/dev/hdc3