topic Re: Mirrored Boot Device in Operating System - HP-UX

Mirrored Boot Device

Steve Andrews_6 — Mon, 08 Oct 2007 08:13:09 GMT

We are running HP-UX 11.11 with MirrorDisk/UX and we have a good Boot mirrored set. If we run lvreduce -m 0 on the LV's to break the mirror will both devices still be bootable?

Re: Mirrored Boot Device

Steven E. Protter — Mon, 08 Oct 2007 08:19:41 GMT

Shalom,

Yes both devices should still be bootable, if you are sure they mirror set is good.

I recommend however you test boot each disk set individually to be certain.

SEP

Re: Mirrored Boot Device

Torsten. — Mon, 08 Oct 2007 08:28:52 GMT

If you reduce the mirror (lvreduce) you will delete the data from the disk!

Don't know what you want to do, but have a look at "man lvsplit".

Re: Mirrored Boot Device

Kevin Wright — Mon, 08 Oct 2007 09:16:20 GMT

no, you may want to look at lvsplit/lvmerge.

Re: Mirrored Boot Device

A. Clay Stephenson — Mon, 08 Oct 2007 09:28:01 GMT

If you run lvreduce -m 0 at most one disk will be bootable. If you were a little sloppy in your commands and specified the wrong physical path during the lvreduce, you could actually end up with no bootable disks.

If you are doing something like replacing the OS then perhaps the easiest method is to simply remove one of your boot disks and perform no LVM commands. You will have two fully bootable disks although the -lq option will be needed in your boot string but that should have already been done as part of your mirroring scheme. With one disk physically removed, you would have to work very hard to destroy the data on it.

Re: Mirrored Boot Device

Tim Nelson — Mon, 08 Oct 2007 09:41:04 GMT

lvreduce will only remove the volume group and lvol info on the reduced disk, not delete the data on the disk.
You still will not be able to boot the second disk though.

lvsplit will require you to mount the lvol#'b' lvols and make some mods to /etc/fstab and lvlnboot info.

The easiest is to yank the disk. Assuming you boot with without quorum. Do your upgrade. If you wish to go back. Remove disk1, insert disk2 and boot from that with -lq option. ( -lq option should always be set anyway ).

Re: Mirrored Boot Device

Steve Andrews_6 — Tue, 09 Oct 2007 07:37:41 GMT

Thank you for the input, it looks like one person says yes both are bootable and four state lvreduce will cause at leat one device to lose boot ability. We are working on an N-Class system, so we cannot pull a disk at least not easily. The lvsplit looks very cumbersome and risky, so we may just rely on Ignite. I am very surprized HP has not addressed such a simple task which would assist greatly in patching and upgrades. I have also opened a ticket with HP Support to get some additional input.

Re: Mirrored Boot Device

Torsten. — Tue, 09 Oct 2007 08:20:47 GMT

You did still not say what you really want to do.

HP's solution for patching and related things is called "dynamic root disk", see

http://docs.hp.com/en/5992-2905/index.html?jumpid=reg_R1002_USEN

Anyway, if you want to safe one disk while changing anything on the other, consider to shutdown the server and pull one disk - disks in a N4000 (aka rp7400) are able to hot-plug. You need just to open the rear "door".

Re: Mirrored Boot Device

Steve Andrews_6 — Tue, 09 Oct 2007 08:27:31 GMT

More information -
We are going to patch one of our systems in Montreal Canada. I am in the US and there is no hands on support in Canada.

Re: Mirrored Boot Device

Steve Andrews_6 — Tue, 09 Oct 2007 08:28:15 GMT

More information
We are going to patch one of our systems in Montreal Canada. I am in the US and there is no hands on support in Canada.

Re: Mirrored Boot Device

Steve Andrews_6 — Tue, 09 Oct 2007 09:40:36 GMT

Once again thanks everyone for your input. It looks like patching 11.11 on an N-Class remotely will be a bit of a task. I will probably rely on the Ignite backup, but I will also wait to hear from HP to get their input and assign points accordinly.

Re: Mirrored Boot Device

Torsten. — Tue, 09 Oct 2007 09:47:12 GMT

IMHO, this is your solution (besides ignite):

"Dynamic Root Disk (DRD) is a software tool containing a set of commands that enable you to clone a system image to another hard disk and modify the image without shutting down the system. DRD significantly reduces system downtime and allows you to do software maintenance during normal business hours.

Using DRD, you can apply patches to the cloned (inactive) system image without affecting the active system image. When modifications are complete, you can reboot (restart) the system using the modified system image. If you do not want to switch images immediately, you can leave both images in place, ready to be switched later."

http://docs.hp.com/en/5992-2905/ch01s01.html?btnNext=next%A0%BB

Re: Mirrored Boot Device

Steve Andrews_6 — Tue, 09 Oct 2007 12:19:58 GMT

Is the Cloning process available in 11.I version 1, 11.11. This link starts at 11.23.

Dynamic Root Disk Administrator's Guide: HP-UX 11i v2, HP-UX 11i v3

Re: Mirrored Boot Device

leelangco_1 — Tue, 09 Oct 2007 20:34:28 GMT

why not make a tape backup befoere patching?