scsimgr SCSI Management and Diagnostics utility on HP-UX 11i v3 (March 2008)

# scsimgr set_devid -D /dev/rdisk/disk20 "Engineering department disk20"

Do you really want to set device id? (y/n)? y

scsimgr: ERROR: LUN /dev/rdisk/disk20 does not support Device Identifier

# scsimgr get_devid -D /dev/rdisk/disk20

scsimgr: ERROR: LUN /dev/rdisk/disk20 does not support Device Identifier

To assign the alias “Engineering - XPD08934-1” to disk device disk1

# scsimgr save_attr -D /dev/rdisk/disk1 -a alias="Engineering - XPD08934-1"

Value of attribute alias saved successfully

To view the alias assigned to disk1

# scsimgr get_attr -D /dev/rdisk/disk20 -a alias

SCSI ATTRIBUTES FOR LUN: /dev/rdisk/disk1

name = alias

current = Engineering - XPD08934-1

default =

saved = Engineering - XPD08934-1

Validating online replacement of devices and SAN reconfigurations

When a LUN with a different WWID is discovered through an existing lunpath, to prevent data

corruption, the SCSI stack puts the lunpath Last Open or Close (SPOC) state in “authentication

failure”. In this state the lunpath cannot be used for I/O transfer. The lunpath remains in this state until

the system administrator validates the change.

Notes:

• Various SAN reconfigurations may result in lunpath “authentication failure”. When that

happens, the mass storage stack logs a message in /var/adm/syslog/syslog.log and on the

console, to alert the user. The user should rely on these messages and should apply the action

recommended. Usually the action consists of running the ‘scsimgr replace_wwid’

command.

• For disk arrays, if the WWID of the LUN representing the array controller (that is, LUN 0)

changes, all lunpaths of that target port go to the 'NO_HW' state on a subsequent ioscan,

resulting in a loss of access to the array controller. This causes the host operating system to no

longer probe for LUNs behind that array controller, so the LUNs behind the controller also go

to the 'NO_HW' state.

The following example illustrates an online replacement of a device leading to a lunpath

“authentication failure”. It shows how to recognize the situation and validate the change by running

the appropriate scsimgr commands.