recovering extend based striping mirror

[Chuck Glover]

I have just created a pvg extend based stripe with mirroring. Thanks to these forums I was able to find enough information to justify trying it and to setup. However, what I have not been able to find is instructions on how to replace a disk that is lost. Can some one direct me to so clear instruction on how to replace the disk, re-establish the stripe and the mirror without data loss. It would also be nice to know how the system will switch to the mirror if a drive is lost. I have 2 stripes of 4 disks mirrored. I am assuming (ugh) that I do not have to worry about quorum (sp).

Thanks to all that answer now and have answered so often in the past.

-Chuck

[James R. Ferguson]

Hi CHuck:

Instructions for replacing a failed disk (mirrored or not; hot-swappable or not) can be found in the HP-UX Software Recovery Handbook (via the Knowledge Trees in Maintenance and Support) chapter16 -- LVM

http://www2.itrc.hp.com/service/iv/docDisplay.do?docId=/DE_SW_UX_swrec_EN_01_E/LVM.pdf

Yes, the whole idea of mirroring is that you will be able to (continue) to access and update data if one mirror fails. The quorum applies during volume group activation.

Regards!

...JRF...

[Sridhar Bhaskarla]

Hi Chuck,

Say the disk is c6t5d0. If it can be replace online, then the following procedure would do.

1. Replace the disk
2. Run ioscan and make sure the disk is claimed.
3. Run vgcfgrestore on the disk

#vgcfgrestore -n vg01 /dev/rdsk/c6t5d0
#vgchange -a y vg01
#vgsync vg01

This should put back the stripes as well the mirror.

If you have to shutdown the box prior to replacing the disk, then edit /etc/lvmrc and make AUTO_VG_ACTIVATE=0

This will not activate your vg01 during the boot. So, you will not see "The disk corresponding to volume group..." errors.

Run those three steps again followed by "mount -a" to get your filesystems mounted. Revert back the changes to your old lvmrc.

-Sri

[Sridhar Bhaskarla]

Hi Chuck,

I would have added these precautions. Take backup of your data while it is still up and running. Also create a make_tape_recovery tape just in case if you get into unknown boot issues.

-Sri

[Michael Steele_2]

Follow Sridhar's advice and then restore the data from tape.

This is the problem with raid 0, no mirror. Mirroring doesn't come in until raid 1.

Because of this problem a lot of time you'll see raid 10 which is raid 0 and 1 combined. For example, that's striped disks plus another 5 acting as the mirrors.

Look into LVM stipe and mirror with -D and 1 mb stipe extents.