Unique identifier for SAN disk but reproducable at OS level

[Ian Dennison_1]

I am moving to an EMC Array which requires moving SAN Ports. When I do this the disk device paths change (as expected).

Is there a unique identifier that I can reference at the HP-UX level on each device? I cannot see the WWN of the LUN using vendor tools (we are a pvlinks setup), is there another way to track the disk by a unique identifier? I need to reimport the disks back to their VGs after the move, with something more definitive than "vgscan".

Share and Enjoy! Ian

PS. Any posting to reference using PowerPath will result in zero points.

[Torsten.]

Why not do a vgimport with a mapfile (including VGID)?

[kevin_m]

If you have EMC Solutions Enabler installed, run the command 'symdev list -wwn | grep -v "Not Visible"'.

[kevin_m]

Disregard - I misread that you're migrating to an EMC and not currently using it.

[Ian Dennison_1]

Torsten,

With the device files changing path, the mapfiles are rendered unusable, unless you know of a way around this?

trusting in "vgscan" is a little too risky for me.

Share and Enjoy! Ian

[Torsten. · Accepted solution]

Use

# vgexport -v -s -m /tmp/vgXX.map vgXX

while importing the system identifies the disks using the VGID, you don't need to specify the disk device.

[Matti_Kurkela]

If you're using Torsten's suggestion (vgexport with the -s option), remember that you must use -s with vgimport also to detect disks by VGID.

If you use vgimport -s, there is no need to list the PVs manually: the system reads the VGID from the map file, then examines every PV it currently sees. All the PVs with the correct VGID are automatically included in the import operation. If the same PV is seen through multiple paths (=multipath LUN), the first discovered path becomes the primary one and all the other paths are listed as alternate paths.

We've been using this trick in multiple storage migrations. It works very well.

Only HP-UX 11.31 can display WWNs directly; read the man page of ioscan if you have 11.31.

There is a free "inq" tool available from EMC:

ftp://ftp.emc.com/pub/elab/inquiry/

Get the newest version: currently it seems to be v7.0.1.0.

(Note: the inq.hpux1100 binary is for 32-bit HP-UX PA-RISC systems, inq.hpux64 is for 64-bit capable PA-RISC systems, inq.HPUXIA64 is for Itaniums.)

Drop it into a suitable location (/usr/local/bin maybe?), set it executable (chmod a+x) and use "inq. -h" to see a long list of options and their descriptions.

It can list the disks in many ways, either by WWN or even directly by the format used in the configuration of various EMC storage systems.

MK

[Ian Dennison_1]

Both workable answers, thanks gents. problem solved.