Sun Microsystems Sun StorEdge T3, Installation, Operation And Service Manual

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Chapter 3 Operation 3-5
3.2.2.1 RAID 0
Data blocks in a RAID 0 volume are striped across all the drives in the volume in
order. There is no parity data, so RAID 0 uses the full capacity of the drives. There is
no redundancy, however; if a single drive fails, all data on the volume is lost.
TABLE 3-2
shows the data layout in a RAID 0 volume.
3.2.2.2 RAID 1
Each data block in a RAID 1 (1+0) volume is mirrored on two drives, and the blocks
are striped across all the drives in the volume. If one of the mirrored pair fails, the
data from the other drive is used. Because the data is mirrored in a RAID 1
configuration, the volume has only half the capacity of the assigned drives. For
example, if you create a four-drive RAID 1 volume with 18-Gbyte drives, the
resulting data capacity is 2 x 18 = 36 Gbytes.
TABLE 3-3
shows the data blocks in a
RAID 1 (1+0) volume with 9 drives.
3.2.2.3 RAID 5
In RAID level 5, data is striped across the drives in the volumes in segments, with
parity information striped across the drives as well. Because of this parity, if a single
drive fails, data can be recovered from the remaining drives. Two drive failures
cause all data to be lost. A RAID 5 volume has the data capacity of all the drives in
the logical unit less one. For example, a 5-drive RAID 5 volume with 18-Gbyte drives
TABLE 3-2
RAID 0 Data Blocks
1
1. Block numbers are written in hexadecimal notation.
Stripe Drive1 Drive2 Drive3 Drive4 Drive5 Drive6 Drive7 Drive8 Drive9
0 0 1 2 3 4 5 6 7 8
1 9 A B C D E F 10 11
2 12 13 14 15 16 17 18 19 1A
TABLE 3-3
RAID 1
(1+0)
Data Blocks
1
1. Block numbers are written in hexadecimal notation.
Stripe Drive1 Drive2 Drive3 Drive4 Drive5 Drive6 Drive7 Drive8 Drive9
0 0 1 2 3 4 5 6 7 8
1 1 2 3 4 5 6 7 8 0
2 9 A B C D E F 10 11