Comment 148 for bug 599255

You should bear in mind that fakeraid puts your data at risk. In the event of a crash or power failure, some data can be written to one disk and not the other. When the system comes back up, a proper raid system will copy everything from the primary to the secondary disk, or at least the parts of the disk ( if you have a write intent bitmap ) that were dirty at the time of the crash, and only allow reads from the primary disk until that is complete. Fake raid does neither of these, so which disk services a read request is a toss up so the system might read the old data on one disk or the new data on the other disk, and this can flip flop back and forth on a sector by sector basis, causing all sorts of filesystem corruption.