When a disk block goes bad, the usual outcome is a data loss. But sector
sparing or cluster remapping can be combined with fault-tolerant volumes to
mask the failure of a disk block. If a read fails, the system reconstructs the
missing data by reading the mirror or by calculating the exclusive or parity
in a stripe set with parity. The reconstructed data are stored in a new location
that is obtained by sector sparing or cluster remapping.