and one raid 1 array over 2 discs
Which raid is this one. Is it mirroring? One of your components may not have redundancy which would corrupt the filesystem on the lvm partition.
On the RAID 5 arrays, it sounds like you have some hot spares installed. The spare should be setup and switched in if a problem is detected on one of the drives.
However, you haven't supplied much in details on them. For example--are these raid-5 arrays linux-raid, or hardware controlled? Are they hot-swappable scsi drives?
Hot swappable drives can be repaired simply by replacing the bad disk.