3
Planning Applications, LUNs, and Storage Groups
3-15
Planning File Systems and LUNs with Shared Switched Storage
LUN ID. The LUN ID is a hexadecimal number assigned when
you bind the disks into a LUN. By default, the ID of the first LUN
bound is 0, th e second 1, a nd so on. Ea ch LUN ID mu st be unique
within the storage system, regardless of its Storage Group or
RAID Group.
The maximum number of LUNs supported on one host-bus
adapter depends on the operating system.
RAID Group ID. This ID is a hexadecimal number assigned
when you create the RAID Group. By default, the number of the
first RAID Group in a storage system is 0, the second 1, and so on,
up to the maximum of 1F (31).
Size (RAID Group size). Enter the user-available capacity in
gigabytes (Gbytes) of the whole RAID Group. You can determine
the capacity as follows:
For example,
•A five-disk RAID 5 or RAID 3 Group of 36-Gbyte disks holds
144 Gbytes;
•An eight-disk RAID 1/0 Group of 36-Gbyte disks also holds
144 Gbytes;
•A RAID 1 mirrored pair of 36-Gbyte disks holds 36 Gbytes;
and
•An individual disk of an 36-Gbyte disk also holds 36 Gbytes.
Each disk in the RAID Group must have the same capacity;
otherwise, you will waste disk storage space.
LUN size. Enter the user-available capacity in gigabytes (Gbytes)
of the LUN. You can make this the same size as the RAID Group,
above. Or, for a RAID 5, RAID 1, RAID 1/0, or RAID 0 Group,
you can make the LUN smaller than the RAID Group. You might
do this if you wanted a RAID 5 Group with a large capacity and
wanted to place many smaller capacity LUNs on it; for example,
to specify a LUN for each user. However, having multiple LUNs
RAID5 or RAID-3 Group: disk-size * (number-of-disks - 1)
RAID 1/0 or RAID-1 Group:(disk-size * number-of-disks) / 2
RAID 0 Group: disk-size * number-of-disks
Individual unit: disk-size