HP StorageWorks HSG80 ACS Solution Software V8.8 for IBM AIX Installation and Configuration Guide (AA-RV1HA-TE, March 2005)

Planning Storage Configurations
84 HSG80 ACS Solution Software V8.8 for IBM AIX Installation and Configuration Guide
■ You can configure up to a maximum of 20 RAID 3/5 mirrorsets per controller
or pair of dual-redundant controllers. Each mirrorset may contain up to 6
members. Refer to "Configuration Rules for the Controller", page 65, for
detailed information on maximum numbers. 30 RAID 3/5 and RAID 1
mirrorsets are permitted, however, there is limit of no more than 20 RAID 3/5
mirrorsets in such a configuration.
■ Both write-back cache modules must be the same size.
■ A mirrorset should only contain disk drives of the same capacity.
■ Spread mirrorset members across different device ports (drive bays).
■ Mirrorsets are well-suited for the following:
— Any data for which reliability requirements are extremely high
— Data to which high-performance access is required
— Applications for which cost is a secondary issue
■ Mirrorsets are not well-suited for the following applications:
— Write-intensive applications (a performance hit of 10 percent occurs)
— Applications for which cost is a primary issue
RAIDset Planning Considerations
RAIDsets (RAID 3/5) are enhanced stripesets—they use striping to increase I/O
performance and distributed-parity data to ensure data availability. Figure 28
shows an example of a RAIDset that uses five members.