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

Planning Storage Configurations
89HSG80 ACS Solution Software V8.8 for IBM AIX Installation and Configuration Guide
unpartitioned storageset or device. Partitions are separately addressable storage
units; therefore, you can partition a single storageset to service more than one user
group or application.
Defining a Partition
Partitions are expressed as a percentage of the storageset or single disk unit that
contains them:
■ Mirrorsets and single disk units—the controller allocates the largest whole
number of blocks that are equal to or less than the percentage you specify.
■ RAIDsets and stripesets—the controller allocates the largest whole number of
stripes that are less than or equal to the percentage you specify.
— Stripesets—the stripe size = chunk size × number of members.
— RAIDsets—the stripe size = chunk size × (number of members minus 1)
An unpartitioned storage unit has more capacity than a partition that uses the
whole unit because each partition requires a small amount of disk space for
metadata.
Guidelines for Partitioning Storagesets and Disk Drives
Keep these points in mind when planning partitions for storagesets and disks:
■ Each storageset or disk drive may have up to eight partitions.
■ In transparent failover mode, all partitions of a particular container must be on
the same host port. Partitions cannot be split across host ports.
■ In multiple-bus failover mode, all the partitions of a particular container must
be on the same controller. Partitions cannot be split across controllers.
■ Partitions cannot be combined into storagesets. For example, you cannot
divide a disk drive into three partitions, then combine those partitions into a
RAIDset.
■ Just as with storagesets, you do not have to assign unit numbers to partitions
until you are ready to use them.
■ The Clone utility cannot be used with partitioned mirrorsets or partitioned
stripesets. (See "Creating Clones for Backup", page 179, for details about
cloning.)