Mass storage stack, native multipathing, and agile naming

The mass storage stack manages I/O devices. In HP-UX 11i v3, the mass storage stack provides native multipathing and agile naming.

With agile naming, rather than being named by the hardware path to the object, I/O devices are named for actual object names. Because these device paths change dynamically, native multipathing provides a single virtualized path that represents multiple paths to single device.

To support the mass storage stack and native multipathing of HP-UX version 11.31, the type attribute of related host objects must be specified as hpux. Although Device Special File (DSF) naming and physical volume links (PVLinks) are supported by HP-UX version 11.31, use the agile naming and native multipathing with the system. For more information about native multipathing support and mass storage stack support for HP-UX version 11.31, see the related Hewlett-Packard publications.

To discover and show all hardware paths and persistent DSFs of the attached disks, use the HP-UX version 11.31 command ioscan –fnNC disk. The system volumes are discovered as IBM 2145 disks.

To determine the open or closed state of paths to a system volume, use the HP-UX version 11.31 command scsimgr get_info all_lpt. The value for the worldwide ID (WWID) in the output of scsimgr matches the unique identifier (UID) of the volume on the system (volume_UID). Also, HP-UX version 11.31 September 2007 release and later implements the T10 ALUA support. Implicit ALUA support is integrated to the HP-UX host type of the system releases.

To show the asymmetric state of paths to system nodes, use the HP-UX version 11.31 command scsimgr. The asymmetric state of paths to preferred node of the LUN is shown as ACTIVE/OPTIMIZED in the output from the scsimgr command. This value of paths to nonpreferred nodes is displayed as ACTIVE/NON-OPTIMIZED. The following examples show the output of the scsimgr command:

# scsimgr get_info all_lpt -D /dev/rdisk/disk1484
STATUS INFORMATION FOR LUN PATH : lunpath993
Generic Status Information

SCSI services internal state = STANDBY
Open close state 	= STANDBY
Protocol	= fibre_channel
EVPD page 0x83 description code	 = 1
EVPD page 0x83 description association = 0
EVPD page 0x83 description type	 = 3
World Wide Identifier (WWID)	= 0x600507680184000060000000000005d4
Total number of Outstanding I/Os	= 0
Maximum I/O timeout in seconds	= 30
Maximum I/O size allowed	 = 2097152
Maximum number of active I/Os allowed 	= 8
Maximum queue depth	= 8
Queue full delay count	 = 0
Asymmetric state	= ACTIVE/NON-OPTIMIZED
Device preferred path	= No
Relative target port identifier	 = 256
Target port group identifier 	= 1


STATUS INFORMATION FOR LUN PATH : lunpath990

Generic Status Information

SCSI services internal state = ACTIVE
Open close state	= ACTIVE
Protocol	= fibre_channel
EVPD page 0x83 description code	 = 1
EVPD page 0x83 description association 	= 0
EVPD page 0x83 description type	 = 3
World Wide Identifier (WWID)	= 0x600507680184000060000000000005d4
Total number of Outstanding I/Os	= 0
Maximum I/O timeout in seconds	= 30
Maximum I/O size allowed	 = 2097152
Maximum number of active I/Os allowed = 8
Maximum queue depth = 8
Queue full delay count	 = 0
Asymmetric state 	= ACTIVE/OPTIMIZED
Device preferred path	= No
Relative target port identifier	 = 0
Target port group identifier = 0

The Dynamic LUN expansion feature in HP-UX version 11.31 supports system volume expansion. To use this feature, the system expandvdisksize command expands the capacity of a volume. For more information about host-side operations, see the Hewlett-Packard publication HP-UX System Administrator's Guide: Logical Volume Management: HP-UX 11i Version 3.