RAID and Subsystem Architectures
RAID 5 - Protection
Parity recovers data,
but what about writes during the time
the hot spare rebuilds. RAID 0 ?
Block C1 Block C2 Parity Block C3
Block B4 Block B5 Block B6 Pa
Parity Block B1
Block A7 Parity
Block B2 Block B3
Block A8 Block A9
Block A4 Block A5 Parity Block A6
Block A1 Block A2 Block A3 Parity
RAID 5 (block striping with distributed parity):
A single disk failure does not mean data loss but it does leave us with a
write problem. We have choice of writing RAID 0 but that is not reliable.
Writing temporary parity to a reserved part of the hot spare is an option
but prolongs rebuild time. Writing to some reserved part of the
subsystem admin space is another option but eats up more storage.
This is an increasing concern as disk drives get bigger.