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LVM - vgexport/vgimport

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Deepak Seth_1
Regular Advisor

LVM - vgexport/vgimport

I have a following sceniero

DISKS VGS

A vg1
B vg1
C vg2
D vg2
E vg3
F vg3
G vg4
H vg4

Inorder to get the maximum performance benefit , i would like to change my phy volume under the vg's to

A vg1
G vg1
B vg2
H vg2
C vg3
F vg3
D vg4
E vg4

I know this can be achived using vgexport/vgimport command . Is this correct way

1. vgexport -p -m vg1.map /dev/vg1
2. vgchange -a n /dev/vg1
3. vgimport -m vg1.map /dev/vg1 /dev/dsk/A /dev/dsk/G
4. vgchange -a y /dev/vg1

Pls. correct me and let me know in case i need to take any precautions.

thanx/deepak
7 REPLIES
Denver Osborn
Honored Contributor

Re: LVM - vgexport/vgimport

Deepak,

In your scenerio the only way the vgexport/vgimport would work is if you are planning on moving disk drives to new controllers and changing the target id.

If vg1 contains A and B, you can't do an import for vg1 and specify disk A and G because Disk G belongs to vg04. Had you planned on physically moving disks arround?
Deepak Seth_1
Regular Advisor

Re: LVM - vgexport/vgimport

yes , i will be moving the 4 disks to a different controller - A,B,C,D .
however E,F,G,H will reamin on the existing . if this doesn't work , suggest me some other alternative.
Denver Osborn
Honored Contributor

Re: LVM - vgexport/vgimport

Here's what I'd suggest;

Unmount filesystens then deactivate the VGs
# vgchange -a n /dev/vg1
# vgexport -v -s -m /tmp/vg1.map /dev/vg1

-now shutdown box and make your changes

After box is backup and online, use vgimport

# mkdir /dev/vg1
# mknod /dev/vg1/group c 64 0x0?0000
(group minor number will be unique)
# vgimport -v -s -m /tmp/vg1.map /dev/vg1
# vgchange -a y /dev/vg1
# mount -a

Do this for each vg you are moving around PVs to. If you use the -s with the -m option you won't need to know disk devices files for the import.
Deepak Seth_1
Regular Advisor

Re: LVM - vgexport/vgimport

just clicked something , yes i can move the both sets of 4 disk to differnet controller.

DISKS
ABCD - controller 1 to controler 2
EFGH - controller 2 to controller 3

Now is it possible ?
Denver Osborn
Honored Contributor
Solution

Re: LVM - vgexport/vgimport

either way I would use the steps from above. vgexport, move disks, vgimport. The results would be the same.
Deepak Seth_1
Regular Advisor

Re: LVM - vgexport/vgimport

u are saying that after putting the disks to new controller. i have to do mkdir dir and mknod again. But since /dev will remain same after moving the disk to different controllers , then mkdir/mknod will not work for the same vg name.

Also u have not specify the new disks while doing the vgimport.

How this will work ?
Deepak Seth_1
Regular Advisor

Re: LVM - vgexport/vgimport

thanx for your help. pls. ignore my last reply. I was using -p with vgexport and hence it was not removing the vg from lvmtab and /dev.