I'm putting together a cheap NAS box and I've read some articles about raid5 not being as robust as I'd imagined. I wanted to get some answers to the following questions before I proceed. I'm proposing the following setup: 1 disk for the OS, 3 disks for the array, Linux software raid to manage the array as raid 5, LVM on top to carve out partitions, some form of encryption on some partitions (probably encfs because I'm used to it).
With three disks managed as raid 5 under Linux, if there is a catastrophic failure of one of the disks and also an unrecoverable read error on another of the disks, is it possible to recover all data on the array apart from the block with the unrecoverable read error? Can I read from a raid array with one disk removed?
If there is a bad sector on one of the disks can I determine which disk that bad sector is on and recover the data from the other two disks?
If I encrypt the whole raid array does this change the answers to the above? My understanding of encryption is poor, but I thought that any error in encrypted data would have knock on effects on the rest of the data. I imagine this would depend on the encryption being used.