HP StorageWorks Command Console V2.5 User Guide (AA-RV1UA-TE, March 2005)

Table Of Contents
Glossary
136 Command Console V2.5 User Guide
RAID 0+1 RAID 0+1 combines the striping of RAID 0 and the mirroring
of RAID 1 to provide the best combination of high performance
and high availability. A RAID 0+1 virtual disk is also known as
a striped mirrored virtual disk.
In a RAID 0+1 virtual disk, each RAID 0 stripe is mirrored to
one or more duplicate device sets. This technique allows much
faster read and write performance than does reading and writing
to a single device. A six-device, RAID 0+1 virtual disk has
potentially three times the bandwidth of a single device because
three separate, small pieces of host data move in parallel.
In addition, the data is completely mirrored to one or more
device sets so there is complete data redundancy for very high
availability.
A RAID 0+1 virtual disk offers the highest performance and the
highest availability of any RAID virtual disk type, but its cost is
high. Such a configuration requires at least twice the number of
devices that a RAID 0 configuration requires.
RAID 1 RAID 1 is the industry-standard term for device mirroring. A
RAID 1 virtual disk is also called a mirrored virtual disk.
In a RAID 1 virtual disk, host data is written as a single large
block to one device and the data is mirrored to one or more
duplicate disks.
A RAID 1 virtual disk provides very high availability because
the data is completely mirrored to one or more devices. Its
performance is no better than that of a single device, however,
because the data is transferred as one large block to and from
these devices.