Determining if a physical volume is managed by UDID or IEEE

Determine if a physical volume is or has the capability of being managed by unit device identifier (UDID) or IEEE.

In order to determine if a physical volume is or can be managed by the UDID format, the following must be verified:

If it is an existing Virtual I/O Server LUN, determine if its format is UDID.
If it is a LUN to be moved to Virtual I/O Server, first verify that the Virtual I/O Server is prepared to see that LUN as a UDID LUN by checking it at the source host.
Note: Moving a physical disk to a Virtual I/O Server that is not capable of managing the device using UDID may result in data loss. In this case, backup the data prior to allocating the LUN to the Virtual I/O Server.

To determine if a device has a UDID, complete the following steps:

Note: These instructions are for Virtual I/O Server. For AIX®, omit step 1 and follow the same instructions.

Type oem_setup_env.

Type odmget -qattribute=unique_id CuAt. The disks that have a UDID are listed. Output similar to the following is displayed:

CuAt:
	name = "hdisk1"
	attribute = "unique_id"
	value = "2708ECVBZ1SC10IC35L146UCDY10-003IBMscsi"
	type = "R"
	generic = ""
	rep = "nl"
	nls_index = 79

CuAt:
	name = "hdisk2"
	attribute = "unique_id"
	value = "210800038FB50AST373453LC03IBMscsi"
	type = "R"
	generic = ""
	rep = "nl"
nls_index = 79

To determine whether a device has an IEEE volume attribute identifier, run the following command: lsattr -l hdiskX. Disks with an IEEE volume attribute identifier have a value in the ieee_volname field. Output similar to the following is displayed:
```
...
cache_method   fast_write                      Write Caching method
ieee_volname   600A0B800012DD0D00000AB441ED6AC IEEE Unique volume name
lun_id         0x001a000000000000              Logical Unit Number
		...
```
If the ieee_volname field does not appear, then the device does not have an IEEE volume attribute identifier.
Note: DS4K and FAStT storage that are using the Redundant Disk Array Controller (RDAC) driver for multipathing are managed using an IEEE ID.