topic Re: About mirror in Operating System - HP-UX

About mirror

Ian lee — Sat, 15 Feb 2003 03:42:40 GMT

Hi,everyone,I want to make mirror of Root,Boot,and Dump volume,but my vg00 reached its MAX_PE,and I can't add a disk to vg00,now I build vg03,put this disk into vg03,can I make Root,Boot,and Dump volume mirror to vg03?

thanks
david

Re: About mirror

Sridhar Bhaskarla — Sat, 15 Feb 2003 03:56:35 GMT

Hi David,

MAXPE is defined per PV. If you didn't override it during the installation, then MAXPE=Size_of_Disk/PE_Size. So, if you add a bigger disk later, only MAXPE extents will be allocated from it. The rest of the space will be unusable.

You cannot mirror logical volumes across volume groups. The best and safeway to recreate vg00 with a bigger PE is through make_tape_recovery. Install Ignite UX, create a make_tape_recovery tape and recover the system from the tape. Once IUX is loaded, you can use the command

/opt/ignite/bin/make_tape_recovery -v -i -x inc_entire=vg00 -f /dev/rmt/0m

This will create the ignite tape. Boot from the tape and you will get into interactive install session. Select your boot disk as the new disk and it will recover the OS on the new disk. Once everything is up and running, you can add the old boot disk into vg00 and extend the mirrors.

If something fails, you can always boot from the old disk.

-Sri

Re: About mirror

A. Clay Stephenson — Sat, 15 Feb 2003 04:47:59 GMT

Sorry, you are not going to be able to mirror across vg's. Max PE's is on a per disk basis and is set when the vg is created. You should have no trouble mirroring your existing vg as long as the disk you are adding is at least as large as your boot disk. If you are adding a larger disk, you will wind up with unused (and unavailable disk blocks) but it will work.

Re: About mirror

Rajeev Shukla — Sat, 15 Feb 2003 05:53:04 GMT

Hi David,
Its not possible to make vg03 as bootable and more over if you go through the documentation of mirroring LVM the you'll see to mirror a LV they need to be in same VG. Across VG mirroring is not possible.

Rajeev

Re: About mirror

monasingh_1 — Tue, 18 Feb 2003 00:02:50 GMT

You could do following:

01. pvcreate -B -f /dev/disk_in_question
02. mkboot /dev/disk_in_question
03 mkboot -a "hpux" /dev/disk_in_question
04 create a vg on /dev/disk_in_question
05 create LV same as vg00 on /dev/disk_in_question

remeber to create LV with -C y -r n for boot root ans swap.
06 now copy everything from vg00 to respective LVs on new LVs on disk_in_question
07 update the fstab on of the root vol of disk in question.

This way you can at least have a boot disk with everything intact....

Repeat step 6 and 7 on regular basis till you can do re-installation using make_recovery.

Hope this helps...

Re: About mirror

T G Manikandan — Tue, 18 Feb 2003 08:45:53 GMT

David,

The MAX_PE limit can be overcome by igniting a tape using IGNITE and then using that tape to change the settings of the vg00 VG.

But even you do all this and increase the MAX_PE and include the bigger size hard disk into VG00 ,if you use it for mirroring with the existing hard disk then still you will face a situation where you can mirror only the amount of the smaller hard disk size.

The best option would be to include a hard disk with the equal size of the existing VG00 and mirror them or replace all the vg00 hard disks with a larger size.

Revert