How to break a pair of mirror

[Kang Sun_1]

Greetings!
My bootable mirror volumes contains two disks of different sizes. I need to break the mirror and replace the smaller disk with another so the two disks are of the same size. My questions are
1. How to make sure the mirror is complete and each side of mirror comtains all data and configuration information needed.
2. Should I just to pull out the smaller disk to simulate a disk failure while the OS is running, or any better way?
3. The replacing disk also contains bootable images. Should erase the whole disk before using it as a replacement?
I saw instructions on how to repare a broken bootable mirror, I am not sure if I should follow the same proceudre to replace a side of mirror purposely.
Thanks!
-- Kang

[Sanjay_6]

Hi,

I would suggest, you shutdown the system and remove the mirror disk, replace it with bigger disk and then use the steps outlined in replacing a failed mirror disk. This way you would still have the mirror disk to fall back on, if necessary.

However i hope, you are aware of the limitation on the size of the disk that you can add to an existing vg. check the vgdisplay output for the root vg, vg00 and do some math.

max_PE_per_PV * PE_size would give you the max size in MB for a disk that can be added into this VG.

Since you already seem to have instructions on how to replace a root mirror i'm not suggesting anything abt that.

Hope this helps.

regds

[Kang Sun_1]

Thank you for the prompt reply.

Actually the original boot disk (18GB) is from a rental box, which I need to return. The new box came with two 36GB disks, and I already used one as the mirror, and I like to use the other one to replace the 18GB one.

Max PE per PV * PE Size is 17400MG, which is proabably caculated exactly for the 18G disk. The system seems to let me mirror the 18G disk with a 36G disk (I hope the mirror is OK). If eventaully I I have two 36G disks in the mirror, would I be able to increase MAX PE per PV or PE Size?

-- Kang
-- Kang

[Sanjay_6]

Hi Kang,

Seems like that though the disk that is there as part of the mirror is 36GB, you are only using 18GB of it. The rest is unused.

You cannot increase the value of these parameters. They are created at the time of installtion for VG00 and at the time of creation for any other vg.

The only way you can use the whole of 36GB is by doing a reinstallation. One way to do this is to take a ignite backup (take two copies) and then reinstall the OS. remember you have to do some stuff to remirror root, it is not automatic, though the system on which the image is being created may have root mirror.

Here is a link to the ignite product site, check the faq,

http://www.software.hp.com/products/IUX/index.html

Download and install ignite, if you don't have it installed on your system. Search the forum for ignite keyword and you'll see lots of questions on how-to

Hope this helps.

regds

[Suraj_2]

Hi

As your root VG contains two different size disks, you are allowed to use the disk maximum size of the lowest in the VG.
Now if you want to make the root VG to support big size disks , you have to reinstall the OS using the Ignite Utility as mentioned. You can also try the procredure mentioned in the attached document which allows you to increase the root size without reinstalling.

Hope this helps

Rgds
Suraj

[Nguyen Anh Tien]

1.)To make sure how much percent is complete when lv is mirroring. you can use
#lvdisplay -v /dev/vgxx/lvxxx.
--- Distribution of logical volume ---
PV Name LE on PV PE on PV
/dev/dsk/c2t0d0 3 3

--- Logical extents ---
LE PV1 PE1 Status 1
00000 /dev/dsk/c2t0d0 00600 current
00001 /dev/dsk/c2t0d0 00601 current
00002 /dev/dsk/c2t0d0 00602 current
If all are current, it mean mirroring is finish.
If some are slate it mean mirroring is still running.
2.) I alway simulate like it.
3.)If this disk is OS disk. You must keep bootable image. otherwise it is no need.
Regard.

Tienna

[Kang Sun_1]

Thank you for all the suggestions!
I just did the replacement of the 18G disk with the 36G one. Now both sides of the mirror in the boot volume are 36G.

I have not yet tried the undocumented way to make the full use of the 36G. I will when there is a need for extra space.

Thanks!

-- Kang