HSG80 ACS Solution Software V8.6 for IBM AIM Installation and Configuration Guide

2–22 HSG80 ACS Solution Software Version 8.6 for IBM AIX Installation and Configuration Guide
Partition Planning Considerations
Use partitions to divide a container (storageset or individual disk drive) into smaller
pieces, each of which can be presented to the host as its own storage unit. Figure 2–17
shows the conceptual effects of partitioning a single-disk container.
Figure 2–17. One example of a partitioned single-disk unit
You can create up to eight partitions per storageset (disk drive, RAIDset, mirrorset,
stripeset, or striped mirrorset). Each partition has its own unit number so that the host can
send I/O requests to the partition just as it would to any 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.
1 Partition 1
2 Partition 2
3 Partition 3
1
2
3
CXO7056A