HP Surestore Disk Array 12h and FC60 - Manual (Page 51)

Disk Array High Availability Features 51
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fails. RAID-0 provides enhanced performance through simultaneous I/Os to multiple disk
modules. Software mirroring the RAID-0 group provides high availability.
Figure 18 illustrates the distribution of user and parity data in a four-disk RAID 0 LUN. The
the stripe segment size is 8 blocks, and the stripe size is 32 blocks (8 blocks times 4 disks).
The disk block addresses in the stripe proceed sequentially from the first disk to the
second, third, and fourth, then back to the first, and so on.
Figure 18 RAID 0 LUN
RAID 1
RAID 1 uses mirroring to achieve data redundancy. RAID 1 provides high availability and
good performance, but at the cost of storage efficiency. Because all data is mirrored, a
RAID 1 LUN has a storage efficiency of 50%.
A RAID 1 LUN consists of exactly two disks configured as a mirrored pair. One disk is the
data disk and the other is the disk mirror. The disks in a RAID 1 LUN are mirrored by the
disk array hardware, which automatically writes data to both the data disk and the disk
mirror. Once bound into a RAID 1 mirrored pair, the two disks cannot be accessed as