Comment GFS and High Availabilty with Shared Disks (Score 1) 43
If you want to share devices between boxes, you'll want to check into GFS for linux (it's in the standard kernel) which will coordinate concurrent access to physical disks at the filesystem layer. GFS will work just as well on either a local (SCSI Y cable) disk array, or on a SAN, but the SAN disk will likely be easier to manage over time, especially considering you won't have to do anything strange to put more than 2 boxes in your HA configuration.
Also, linux-ha has STONITH capabilities (Shoot The Other Node In The Head) to prevent a split cluster from corrupting your filesystem(s).
As far as reliability, HP-UX (I don't think Linux can currently do this) can have dual paths to the same physical device on a SAN. This means you can pull the plug (or trip on the cable) on one of the fibre cards and the other will pick right up. It is possible that the qlogic cards will do this, but I haven't checked.
Also, linux-ha has STONITH capabilities (Shoot The Other Node In The Head) to prevent a split cluster from corrupting your filesystem(s).
As far as reliability, HP-UX (I don't think Linux can currently do this) can have dual paths to the same physical device on a SAN. This means you can pull the plug (or trip on the cable) on one of the fibre cards and the other will pick right up. It is possible that the qlogic cards will do this, but I haven't checked.
