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 RAID 3, 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, the second 1, and so on. Each LUN ID must 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
