User`s guide

StorageWorks RAID Array 200 Controller Installation and Standalone Configuration Utility
6–28 EK–SWRA2–IG. C01
6.6.1 Creating a Drive Group
A drive group is from one to eight drives that operate as a single drive.
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 6–3 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 6–3 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 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:
• Each disk can belong to only one drive group at a time.
• You can create a maximum of 8 drive groups.
• Also, after you create drive groups you must arrange them in the order in
which you want to use them. (You must use all the available space on a
drive group before you can use another one.) So, consider what data you
want to put on which drive group, before arranging your drives, because you
can only delete drive groups in the reverse order in which they were
arranged. For example if you create drive groups a, b and c, and arrange
them in that order, then you must delete drive groups c and b before you can
delete drive group a.