User`s guide

StorageWorks RAID Array 200 Controller Installation and Standalone Configuration Utility
7–20 EK–SWRA2–IG. C01
7.3.1. Creating a Drive Group
You can create a drive at any time. After you initially configure the subsystem,
you can create a drive group with drives that you did not previously configure
into drive groups, or with new drives you add to the subsystem. You can also
create new drive groups with drives that you previously configured into drive
groups by first canceling the existing drive groups that you want to re-organize.
A drive group is from one to eight drives that operate as a single drive. You can
create a maximum of 8 drive groups.
Determine how many drives to use for each drive group based on the following:
• The RAID levels of the logical RAID drives you will create
See Table 7–2 to see the minimum and maximum number of drives allowed
for each RAID level. (You can create multiple logical RAID drives of
varying RAID levels on a drive group.) See Chapter 1 for a discussion of
RAID Levels.
• The amount of disk space you need
Table 7–2 shows the amount of storage available for unique data for each of
the RAID levels.
Also, consider the capacities of each of the individual disks. The capacities
of each of the individual disks are affected by the other disks in a group.
Disk drives of varying capacities are limited to the capacity of the lowest
capacity drive in the drive group. Table 6–4 in Chapter 6 provides examples
of how the capacity of each individual drive affects the capacities of the
other drives in the group. To maximize your disk space resources, use drives
of the same capacity in a drive group.
If you plan to use more than one drive group, remember that each disk can
belong to only one drive group at a time.