Raid 5 Hard disk corruption

It depends on your RAID controller, but most likely it won't support that. It would have to move all the data around to lay it out in a clean way.

You best bet is to either be patient and wait for the other drives, or buy a 4th drive and then you'll have a spare for later.

If you buy a 4th, then you'll install on the one you have now, and then migrate the install over to the RAID once the other drives come in, using something simple like dd. Then that initial disk will be your spare.

I asked a NetApp engineer who was giving us a talk this very question. His answer, more or less, was:

Nobody reads the checksums on reads. There's no point. Reading a checksum means you have to read the entire slice plus checksum, then compute the checksum to verify you have the correct data. Plus the orthoganal checksum if you are running RAID-6 or whatever. It is a total performance killer because it breaks the ability to randomly seek to totally different sectors on different disks at the same time. Similarly, almost nobody reads both sides of a mirror in RAID-1 because if you only read one side you can alternate which side of the mirror you read from so that you get faster throughput, and if you suddenly have a mismatch, which disk do you take as correct and which do you take as broken? All modern RAID systems depend on the on-disk controllers to signal the RAID controller that they are in distress (through SMART or the like), at which point that disk is almost always kicked out of the array. Checksums are used for rebuilding arrays, not for read-verification.