HP Surestore Disk Array 12h and FC60 - Manual (Page 78)

78 Recommended Disk Array Configurations
• Global hot spares - although none of the configurations use global hot spares, their use
is recommended to achieve maximum protection against disk failure. For more
information, see
"Global Hot Spare Disks" on page 61 .
• Split bus operation - With three or fewer disk enclosures, increased performance can
be achieved by operating the disk enclosures in split bus mode, which increases the
number of SCSI busses available for data transfer. However, operating the disk
enclosures in split bus mode may make if more difficult to expand the capacity of the
array. In a split bus configuration, it may be necessary to take down the host, back up
data, and rebind LUNs when adding disk enclosures. If you anticipate the need to
expand your disk array, you may want to consider selecting a configuration that uses
more enclosures operating in full bus mode. In addition to simplifying expansion, this
type of configuration also gives you greater flexibility when creating LUNs.
• Segment size - the recommended segment size is 16
K
byte for RAID 5, and 64
K
byte for
RAID 1 and RAID 0/1.
• Maximum LUNs - A maximum of 30 LUNs can be configured on the disk array.
One Disk Enclosure Configuration
Note A single disk enclosure configuration is not recommended for environments
where high availability is critical. For optimum high availability, at least two
disk enclosures are required. This protect against the failure of a single disk
enclosure.
• Hardware Configuration
– Two disk array controllers connected directly to host Fibre Channel adapters
– One disk enclosure with ten 73 GBytes disk modules
– Disk enclosure configured for split-bus mode (two SCSI channels)
• LUN Configuration
– Five RAID 1 LUNs, each comprising two disks (1+1)
– Each disk in a LUN is on a separate SCSI channel