C-6
AlphaServer 8200/8400 Operations Manual
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:
1. The RAID levels of the logical RAID drives you will create
See Table C-1 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.)
2. The amount of disk space you need.
Table C-1 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 C- 2 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:
1. Each disk can belong to only one drive group at a time.
2. You can create a maximum of eight drive groups.
3. 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.
Creating a drive group requires the following procedures:
1. Defining a drive group
2. Arranging a drive group
First determine how you want to allocate your drive resources and then configure the
drives in your array.
