5
Planning Applications, LUNs, and Storage Groups
5-17
Planning File Systems and LUNs
RAID 3. If you want to use the SP memory for RAID3, check the
box.
RAID Group/LUN Entries
Complete a RAID Group/LUN entry for each LUN and hot spare.
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.
SP owner. Specify the SP that will own the LUN: SP A or SP B.
You can let the management program automatically select the SP
to balance the workload between SPs; to do so, leave this entry
blank.
SP bus (0 or 1). Each FC4700 SP has two back-end buses, 0 and 1.
Ideally, you will place the same amount of load on each bus. This
may mean placing two or three heavily-used LUNs on one bus,
and six or eight lightly used LUNs on the other bus. The bus
designation appears in the disk ID (form bus-enclosure-disk). For
disks on bus 0, you can omit the bus designation from the disk ID;
that is, 0-1-3 and 1-3 both indicate the disk on bus 0, in enclosure
1, in the third position (fourth from left) in the storage 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:
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