LUNZ is defined as :
The logical unit number that an application client uses to communicate with, configure and determine information about an SCSI storage array and the logical units attached to it. The LUN_Z value shall be zero. In the EMC context, LUNz refers to a fake logical unit zero presented to the host to provide a path for host software to send configuration commands to the array when no physical logical unit zero is available to the host.
On an EMC array, the LUNZ device is replaced when a valid LUN is assigned to the HLU LUN0 by the Storage Group. The agent then communicates through the storage device. The user will continue, however, to see LUNz in the Device Manager.
LUNz has been implemented on EMC arrays to make arrays visible to the host OS and PowerPath when no LUNs are bound on that array. When using a direct connect configuration, and there is no Navisphere Management station to talk directly to the array over IP, the LUNZ can be used as a pathway for Navisphere CLI to send Bind commands to the array.
LUNz also makes arrays visible to the host OS and PowerPath when the host’s initiators have not yet logged in to the Storage Group created for the host. Without LUNz, there would be no device on the host for Navisphere Agent to push the initiator record through to the array. This is mandatory for the host to log in to the Storage Group. Once this initiator push is done, the host will be displayed as an available host to add to the Storage Group in Navisphere Manager (Navisphere Express).
LUNz should disappear once a LUN zero is bound, or when Storage Group access has been attained.
To turn on the LUNz behavior on EMC arrays, you must configure the
LUNZ is a placeholder. It is as simple as that. In HP-UX 11.31,
ioscan runs without human intervention. Thus you can end up in a situation where your server can see the storage array, but no LUNs are presented to the server … yet. And thus you get LUNZ. The same applies for 11.23 and below, but it is unlikely that you scan for devices before your storage admin comes along.
You then end up with:
You might also see following in the SYSLOG:
And no matter how many times you do
ioscan -fn, you get no devices. Before you go yelling at your storage admin, then try to remove the LUNZ device:
Then check that the LUNZ device is gone:
Try to get the LUNs onboard:
Check. Lo and behold. They are available now: