EMC CX700 Planning Manual page 112

Planning File Systems and LUNs
5-18 EMC CLARiiON CX300, CX500, CX500i, and CX700 Storage Systems Configuration Planning Guide
Size (RAID Group size). Enter the user-available capacity in
gigabytes (Gbytes) of the whole RAID Group. You can determine
the capacity as follows:
RAID 5 or RAID 3 Group:
RAID 1/0 or RAID 1 Group: (disk-size number-of-disks) / 2
RAID 0 Group:
Individual unit:
For example,
• A five-disk RAID 5 or RAID 3 Group of 73-Gbyte disks holds
292 Gbytes;
• An eight-disk RAID 1/0 Group of 73-Gbyte disks also holds
292 Gbytes;
• A RAID 1 mirrored pair of 73-Gbyte disks holds 73 Gbytes;
and
• An individual disk of an 73-Gbyte disk also holds 73 Gbytes.
LUN size. Enter the user-available capacity in gigabytes (Gbytes)
of the LUN. You can make this the same size as the RAID Group,
described previously. 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 per RAID Group may adversely impact
performance. If you want multiple LUNs per RAID Group, then
use a RAID Group/LUN series of entries for each LUN.
Disk IDs. Enter the IDs of all disks that will make up the LUN or
hot spare. These are the same disk IDs you specified on the
previous worksheet. For example, for a RAID 5 Group in DAE2
on loop 0 (disks 10 through 14), enter 0010, 0011, 0012, 0013, and
0014.
RAID type. Copy the RAID type from the previous worksheet.
For example, RAID 5 or hot spare. For a hot spare (not strictly
speaking a LUN at all), skip the rest of this LUN entry and
continue to the next LUN entry (if any).
If this is a RAID 3 Group, specify the amount of SP memory for
that group. To work efficiently, each RAID 3 Group needs at least
6 Mbytes of memory.
disk-size (number-of-disks - 1)
disk-size number-of-disks
disk-size