Apple Xserve RAID: Using RAID 1.2 Admin and Disk Utility - Manual (Page 39)

Chapter 4 Using Advanced Features of RAID Admin 39
The RAID controller begins restriping data across all the drives. The added drives’
capacity is added to the array as an unmapped slice. To make the added drive or drives
available to the array, merge the slices on that array.
To complete the expansion procedure by merging:
m Return to the Advanced window, select Slicing, and merge the slices on the array that
you just expanded.
See “Merging Slices in an Array” on page 37 for details on merging slices.
Masking RAID Volumes on Multiple Host Systems
(LUN Masking)
If you have two or more host computers connected to an Xserve RAID system through
a switch, you must “map” each LUN to a specific host computer. Mapping a LUN to a
particular host will “mask” that LUN so it is not visible on any other host. This feature is
called “LUN masking.”
You use RAID Admin to map LUNs to host computers. LUN is an acronym for “logical
unit number,” which is a device-addressing scheme associated with arrays and slices.
Note: The Xserve RAID system displays arrays or slices as LUNs on a host computer.
By LUN-masking arrays and slices, you avoid the possibility that more than one host
user could write data on an array and possibly corrupt the array or otherwise lose data.
About the World Wide Port Name
LUN-masking an array requires identifying the host by using the World Wide Port Name
(WWPN) of the host’s fibre channel port. This name is a unique 16-character identifier
assigned to each of the two ports on the Apple Fibre Channel PCI Card. The specific
WWPN you need for an array is the one for the port on the card that is connected to
the RAID controller for your array. (For more information about the Apple Fibre Channel
PCI Card and its connections to the Xserve RAID system, see Chapter 4, “Connecting
Xserve RAID to a Host System and a Network,” in the Xserve RAID User’s Guide.)
You use the Fibre Channel Utility application provided on the Xserve RAID Admin Tools
disc (or use Software Update in System Preferences to update the software) to locate
the WWPN for each port on the Apple Fibre Channel PCI Card.
Note: Fibre Channel Utility replaces the application Fibre Channel lnfo, used previously.