ATTO Technology FastStream SC 5700 - Manual (Page 69)

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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 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.
Data 11 Data 10
Parity 10-12 Parity 10-12
Stripe 2
Stripe 3
Stripe 1
Data 7
Parity 4-6
Parity 1-3
Parity 7-9
Parity 4-6
Data 3
Parity 7-9
Data 6
Data 2
Data 9
Data 5
Data 1
Disk 1 Disk 2 Disk 3 Disk 4
Stripe 4
Data 12
Data 8
Data 4
Parity 1-3
Disk 5