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Break a failing mirrored boot drive

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Michael Leis

Break a failing mirrored boot drive

Im using MirrorDisk/UX and have previously mirrored my boot disk and made it bootable. This has been tested and found to be successful.

My mirror hard drive is failing. EMS is reporting a number of new bad spots on the drive and I want to have HP replace it.

I would reason that I need to break that mirror and then remirror when the replacement drive is put into place.

How would I go about doing that?
Honored Contributor

Re: Break a failing mirrored boot drive

If it is hot swappable, you can just take it out, put new one.

Then check if it claimed in ioscan output, if yes

do vgcfgrestore -n vg00 /dev/rdsk/cxtxdx
vgchange -a y vg00

There is no substitute to HARDWORK
Marvin Strong
Honored Contributor

Re: Break a failing mirrored boot drive

You will beed to lvreduce all logical volumes that are mirrored to the drive in order to break the mirrors.

lvreduce -m 0 lvname


lvreduce -m 0 /dev/vg00/lvol1

I don't think its required to break the mirror before replacing the drive.
However I always do.
Honored Contributor

Re: Break a failing mirrored boot drive


You don't have to reduce the mirror to replace the disk.

Once you have replaced the disk, do a vgcfgrestore to restore the VG info to the disk. Do a "vgchange -a y /dev/vg00" to activate the disk and then do a vgsync for /dev/vg00 to resync the mirror copies.

Try this link from ITRC.

The itrc doc id is KBAN00000347.

Hope this helps.

Honored Contributor

Re: Break a failing mirrored boot drive

Hi Michael,

You dont have to break the mirror and remirror to replace the failed drive

Assuming your hard drive is not hotswappable

1) Shutdown & get the hard drive replaced
2) boot
3) # vgcfgrestore -n vg00 /dev/rdsk/c#t#d#
# mkboot /dev/rdsk/c#t#d#
# mkboot -a "hpux -lq" /dev/rdsk/c#t#d#
# vgsync /dev/vg00


Learn What to do ,How to do and more importantly When to do ?
Steve Post
Trusted Contributor

Re: Break a failing mirrored boot drive

WARNING if these are Jamaica disks with a V-Class box. You might think the disks are hot-swappable. They are NOT.

I had a mirrored data disk, in a set of 8 jamaica disks. Two of the 8 disks were a mirrored vg00. We pulled the bad vg01 disk. Then all 8 disks started to act weird and were trashed.

So now when I think "hot" swappable. I know it's hot. I'll get BURNED. Just a word of warning if you are using a V-class machine with Jamaica disks.

Michael Leis

Re: Break a failing mirrored boot drive

Thank you for all of your help with this issue.

Special credit goes to Sanjay and to Steve Post.

The documentation SanJay specifically pointed me to was very very helpful. The note on the Jamaica drives from Steve Post was also very helpful since I my mirrored root volumes were in a Jamaica box but running on a K420. Nonetheless, I just didn't take any chances, we shut down before doing the swaps... Thanks for the forewarning!

A couple of comments... The document SanJay referred to, in step 4.2, I added the -lq (ell que) parameter to the mkboot -a command. I also needed to do one more mkboot command to copy over the diagnostics information as well. Ultimately, here is what I ran (assume c5t0d0 is my good primary boot disk and c4t6d0 is my mirror boot disk that I replaced):

# vgcfgrestore -n /dev/vg00 /dev/rdsk/c4t6d0
# vgchange -a y /dev/vg00
# mkboot /dev/rdsk/c4t6d0
# mkboot -a "hp-ux -lq(;0)/stand/vmunix" /dev/rdsk/c4t6d0
# lvlnboot -R
# mkboot -b /usr/sbin/diag/lif/updatediaglif -p ISL -p AUTO -p HPUX -p PAD -p LABEL /dev/rdsk/c4t6d0
# vgsync /dev/vg00

After it finished syncing the two drives, I was able to reboot the server and used the BO ALT to boot from my mirror... it worked perfectly.

Again, THANK YOU to ALL of you who contributed to this.
steven pan
Occasional Advisor

Re: Break a failing mirrored boot drive

i can't see this doc
who can show it to me ???

Michael Leis

Re: Break a failing mirrored boot drive

See comments above