change SCSI ID on boot disk

[Marc Ahrendt]

if you have a system with only one disk, then what do you do if you want to change its SCSI ID from 5 to 6?

[A. Clay Stephenson]

Hi Marc:

If you cold install, you will be asked for the boot path. You can also set the primary boot path in the firmware monitor or with the setboot -p command. Man setboot for details.

Now as for setting the actual SCSI ID that is hardware dependent; sometimes with jumpers on the drive itself; sometimes with DIP switches on the back of the enclosure; and sometimes from the front panel.

Clay

[Patrick Wallek · Accepted solution]

If you want to change to SCSI ID of the disk "on the fly" so to speak, that is going to be difficult. Things to consider:

1) Your VG configuration would be invalid. You could probably vgexport and vgimport from withing LVM Maintenance mode.

2) Information obtained from lvlnboot would be invalid. That too could be changed.

3) You'd have to change your default boot path in ISL so that it boots from the correct disk.

If I were going to undertake something like this, I'd consider downloading and installing Ignite/UX http://software.hp.com/products/IUX

and make a make_tape_recovery tape. I'd probably make 2 just to be on the safe side. I'd then shut down the system, change the SCSI ID however is appropriate and boot from the make_tape_recovery tape to reinstall the OS so that everything that is dependent on the SCSI ID of the disk (and the associated device files) is up to date.


But if your system just has one disk, why bother with all that trouble?

[Michael Tully]

Hi Mark,

Why do you wish to change the SCSI ID in
the first place if you only have a single
disk? It is actually better
to leave a disk that has been defined as
ID 6 in any case. Any additional disks
should have 5, 4, 3 etc. Changing the ID
is hardware dependant on the type of drive
that it is, and it difficult to advise
how unless we know exactly what type of
disk that it is.

-Michael

[Panos Agoros]

Hi all,


it's funny but I had a similar problem yesterday: i had to change a root disk's controller & scsi id (from 6 to 4) on a D-class. i've tried several different things but havent been able to restore the LVM configuration. finally, i had to take an ignite backup & restore it, choosing the boot disk's new HW path as the target for the installation.

does anyone has to suggest a workaround for this?

thanks

[Carlos Fernandez Riera]

I agree Michael. Boot disk alone is a SCSI chanel... dont mind what SCSI ID.
___

I guess i avoid to use ignite.
Shutdown.
change SCSI ID
After reboot, stop boot process
SEARCH IPL
BOOT hardware path
Interact with IPL -> Y
hpux -lm
vgexport /dev/vg00
mkdir /dev/vg00
mknod .....
vgimport /dev/vg00
lvlnboot -R

reboot.


See man lnrmboot, and lvlnboot.

[Wim Rombauts]

If you are using a whole-disk configuration (not using LVM) then it's simple. Shutdozn the machine, change the SCS-ID of the disk, restart to boot_admin mode and adjust your primary boot path.

When you're using LVM, there is of cours Ignite/UX, but you can also use the recovery media :
Shutdown the system, change the SCSI-ID and restart the system to boot-admin mode. Then you start from CD ("search ipl", then "boot P?"). Do not interact with IPL.
You can start a recovery shell from here that you can use to change your lvlnboot settings. This is done by chrooting to an lvm root. Choose 'c' in the menu, instructions will follow.
If you're interested, I can lookup the procedure. I use it to boot from a spare rootdisk in case of severe trouble.

[Marc Ahrendt]

it is not critical, but i just wanted to change 5 to 6 to make the system more standard, expect to add a 2nd PV soon to mirror LVs.

basically this system has a bad boot disk, so i wanted to put in a new disk (using ID 6) to cold install on, then recover the data from Legato (will have an ignite tape when done! ...i failed to make one for this system)

Clay: sorry i did not explain better, Patrick guessed right on my intentions
Patrick: thx for the suggestions
Michael: i want to go from 5 to 6, not the reverse
Panos: thx for the warning, hopefully Fernandez's instructions will help us both
Fernandez: thx for the steps, i will try them 1st on a test box
Wim: i am very interested in the procedure u outlined ...is recovery media shipped with support+ CDs?