HPE Community read-only access December 15, 2018
This is a maintenance upgrade. You will be able to read articles and posts, but not post or reply.
Hours:
Dec 15, 4:00 am to 10:00 am UTC
Dec 14, 10:00 pm CST to Dec 15, 4:00 am CST
Dec 14, 8:00 pm PST to Dec 15, 2:00 am PST
cancel
Showing results for 
Search instead for 
Did you mean: 

install with a root mirror

 
Chris Howard
Frequent Advisor

install with a root mirror

We have a HP-UX 11.11 system with mirrored root drive that we want to do a full install of HP-UX 11.23

I want to keep the mirrored disk out of the new install so that we can reboot back to 11.11 if something goes wrong.

Do I need to explicitly break the mirror before the new install?

13 REPLIES
Steven E. Protter
Exalted Contributor

Re: install with a root mirror

Shalom,

You should explicitly break the mirror. That is good practice.

Technically, if you do the new OS install and only include the primary boot disk, you will still be able to manually boot the system at console onto the mirror disk.

As a security measure, have an Ignite make_tape_recovery or make_net_recovery backup at the ready.

SEP
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
Sponsor: http://hpux.ws
Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com
Torsten.
Acclaimed Contributor

Re: install with a root mirror

Shut down, remove the disk, boot with quorum mode and "vgreduce -f" the "missing" disk.

If needed, insert the "old" disk and boot from it again.

Hope this helps!
Regards
Torsten.

__________________________________________________
There are only 10 types of people in the world -
those who understand binary, and those who don't.

__________________________________________________
No support by private messages. Please ask the forum!

If you feel this was helpful please click the KUDOS! thumb below!   
Chris Howard
Frequent Advisor

Re: install with a root mirror

Is there some way to do it without physically removing the disk? I'm working remotely.
R.O.
Esteemed Contributor

Re: install with a root mirror

You can disable it and prevent LVM from using it:

# pvchange -a N /dev/dsk/cXtXdX

Regards,
"When you look into an abyss, the abyss also looks into you"
Torsten.
Acclaimed Contributor

Re: install with a root mirror

This is dangerous.

After a reboot, the disk is activated again and will be synced with the other disk.

So your "backup" is gone.




Another idea:

unmirror the drive and clone it with DRD (no unmirror needed, if you have another empty disk).

In case of trouble boot the DRD clone and you are back in business.

Hope this helps!
Regards
Torsten.

__________________________________________________
There are only 10 types of people in the world -
those who understand binary, and those who don't.

__________________________________________________
No support by private messages. Please ask the forum!

If you feel this was helpful please click the KUDOS! thumb below!   
Chris Howard
Frequent Advisor

Re: install with a root mirror

I'm going to try this on my test machine:


Build root clone Drive A -> Drive B

pvchange -a N Drive A
reboot and do cold install on Drive A
See if I can boot old Drive B

Chris Howard
Frequent Advisor

Re: install with a root mirror

In my experiment, installing on Disk A works fine.

Booting from Disk B gives me errors about missing Disk A. (The disk is still in place and operational.)

I repeated pvchange -a N (disk A)
but still get the error messages.

As long as it is not actually writing to disk A, I think this outcome will work.

Torsten.
Acclaimed Contributor

Re: install with a root mirror

pvchange -a N will disable LVM access, but only until next VG activation (e.g. during a boot). Then the disk will be sync again.

So if you do an installation on the remaining disk, after the next boot the installation disk will be synced to your "backup" disk = no backup anymore.

Hope this helps!
Regards
Torsten.

__________________________________________________
There are only 10 types of people in the world -
those who understand binary, and those who don't.

__________________________________________________
No support by private messages. Please ask the forum!

If you feel this was helpful please click the KUDOS! thumb below!   
Elmar P. Kolkman
Honored Contributor

Re: install with a root mirror

After the installation, the PV has been re-created... so the PV-ID is changed and not accepted anymore by the old vg00 of the 11.11 environment.

This means that the data on both disks is still valid and save, but if you will have to boot from the old disk, you need to specify the '-lq' option (low quorum).
Every problem has at least one solution. Only some solutions are harder to find.
Torsten.
Acclaimed Contributor

Re: install with a root mirror

Elmar, this sounds reasonable.

I was trying to disable a disk that way, changed anything and reboot, then the disk was synced. I agree we have new IDs after a new installation, but not after an upgrade, right?


Hope this helps!
Regards
Torsten.

__________________________________________________
There are only 10 types of people in the world -
those who understand binary, and those who don't.

__________________________________________________
No support by private messages. Please ask the forum!

If you feel this was helpful please click the KUDOS! thumb below!   
Kanagaraj
Regular Advisor

Re: install with a root mirror

//Booting from Disk B gives me errors about missing Disk A. (The disk is still in place and operational.)//

you try boot from Disk B as follows.

stop the booting at ISL>

boot by diskB--> ISL>bo -lq

Problem:
Disk A is present but it doesn't have LVM structure of 11.11 (previous OS)..Now DiskA has new OS 11.23.So DiskB has mirrored info,So quorum will not alow to boot from diskB,this case DiskB should be boot by disable quorum.(bo diskB -lq)
Elmar P. Kolkman
Honored Contributor

Re: install with a root mirror

You get new ID's when the volume group is been re-created... For instance a new install.
It's the same as when you re-install a system with ignite: you also have to re-add the second disk and mirror everything to reinstate the mirrored vg00.
Every problem has at least one solution. Only some solutions are harder to find.
Chris Howard
Frequent Advisor

Re: install with a root mirror



Booting from Disk B, either with or without the '-lq' seems to work ok. I think with '-lq' it is happier during bootup.

After bootup I only get error messages when I run something like 'vgdisplay -v /dev/vg00'.

So I think either way works ok.

It would be really nice to have a more direct split, something like 'lvsplit' to let me peel off everything on that second drive. But I have not found anything like that yet.

I think I have enough to go forward with.
Thanks to everyone.