RAID and Subsystem Architectures RAID Configurations
RAID 5 - Protection
Parity recovers data,
but what about writes during the time the hot spare rebuilds. RAID 0 ?
Block B4 Block C1
Block A7 Parity
Block A1 Block A4
Block C2
Block B1 Block B5
Block A2 Block A5 Parity
Parity Block B6
Block A8 Block B2
Block A3 Parity
Block C3
Block A9 Block B3 Parity
Block A6 Parity
X
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.