ATTO Technology FastStream SC 5700 Installation And Operation Manual page 69

RAID Level 6: striping, two parity blocks distributed among drives
RAID Level 6 increases reliability for mission critical
applications by striping both data and dual parity
across multiple drives, writing data and parity blocks
across all the drives in a RAID group. RAID 6 provides
Disk 1
Stripe 1
Data 1
Stripe 2
Data 5
Stripe 3
Data 9
Stripe 4
Parity 10-12
can tolerate failure of two drives and provides
redundancy during rebuilds.
The ATTO FastStream requires at least four drives to
build a RAID 6 group. Two drives per RAID group are
used for parity protection and are unavailable for data.
Disk 2 Disk 3
Data 2 Data 3
Data 6 Parity 4-6
Parity 7-9 Parity 7-9
Data 10
Parity 10-12
Disk 4 Disk 5
Parity 1-3 Parity 1-3
Parity 4-6 Data 4
Data 7 Data 8
Data 11 Data 12
xxii