Silicon Graphics TP9100, Installation Instructions And User Manual

Page: 78 / 182

62 007-4382-002
3: Using TPM
Expand LUN
RAID expansion allows capacity to be added to an existing RAID set while the controller
is online. No resets are required, and I/Os to other LUNs will be serviced (a little slower).
The following rules and conditions must be met to expand a LUN:
Note: SGI does not support LUN Expansion and MORE operations on the IRIX and
Linux operating systems
1. The most important rule is that you must be using a file manager such as Veritas’
Volume Manager. These file managers allow you to actually use an expanded LUN.
If you wish to attempt an on-line expansion, and your environment is not properly
configured, the request will fail, and you will receive an appropriate error message.
2. During the expansion, which includes re-striping data from the old (smaller) set to
the larger set, the controller continues to service host I/O operation.
3. LUN expansion allows you to add capacity to an existing LUN while the controller
is online with the host(s). For example, a system using a 6-disk RAID5 set can add
another disk to create a 7-disk drive set. This procedure is also referred to by the
acronym MORE.
MORE is supported in the simplex mode of operation only. One controller in a
dual-active controller system must be disabled (failed over). Attempting to do this
operation in a dual-active environment will be rejected.
4. One to six drives can be added to a set at a time. The maximum number of physical
disk drives is eight with 6.14 controller firmware, or 16 with 7.01 and later firmware.
5. You can not have eight LUNs defined with 6.14 controller firmware or 32 LUNs
defined with 7.01 and later controller firmware. The expansion requires one free
LUN in order to execute.
6. You cannot perform an expansion if all eight LUNs are defined with 6.14 controller
firmware or all 32 LUNs defined with 7.01 and later controller firmware.
7. The disk drives being added must be in STANDBY, and must not be part of an array.
8. The capacity of each of the added disk drives must be greater than or equal to the
size of the smallest disk drive in the set.
9. The added capacity parameters are kept in non-volatile memory. In the event of
power loss to this host or to the subsystem, (or a controller failure) the process
automatically resumes when power is restored, or the controller is replaced.