I'm sure others can provide a much more in depth answer but in short...
Not all "file systems" are cluster aware.|
Something like GFS can be active on all nodes at the same time; because it uses a lock manager that makes every node in your cluster "chat" with each other to determine who is writing to the filesystem to keep it from corrupting itself.
In my case, I need xfs (or maybe ext3) for a few reasons; hence I'll be doing "active - passive" on a 2 node cluster - and therefore passing the filesystem and luns back and forth - between "primary vs. standby".
Jonathan Horne wrote, On 3/15/2010 9:04 PM: