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Moving volume group to another Server in Linux



Moving a VG to another server:

To do this we use the vgexport and vgimport commands.

vgexport and vgimport is not necessary to move disk drives from one server to another. It is an administrative policy tool to prevent access to volumes in the time it takes to move them.

1. Unmount the file system
First, make sure that no users are accessing files on the active volume, then unmount it

# unmount /appdata

2.Mark the volume group inactive
Marking the volume group inactive removes it from the kernel and prevents any further activity on it.

# vgchange -an appvg
vgchange -- volume group "appvg" successfully deactivate



3. Export the volume group

It is now must to export the volume group. This prevents it from being accessed on the old server and prepares it to be removed.

# vgexport appvg
vgexport -- volume group "appvg" successfully exported

Now, When the machine is next shut down, the disk can be unplugged and then connected to it's new machine

4. Import the volume group

When it plugged into the new server, it becomes /dev/sdc (depends).

so an initial pvscan shows:

# pvscan
pvscan -- reading all physical volumes (this may take a while...)
pvscan -- inactive PV "/dev/sdc1" is in EXPORTED VG "appvg" [996 MB / 996 MB free]
pvscan -- inactive PV "/dev/sdc2" is in EXPORTED VG "appvg" [996 MB / 244 MB free]
pvscan -- total: 2 [1.95 GB] / in use: 2 [1.95 GB] / in no VG: 0 [0]

We can now import the volume group (which also activates it) and mount the file system.

If you are importing on an LVM 2 system, run:

# vgimport appvg
Volume group "vg" successfully imported

5. Activate the volume group

You must activate the volume group before you can access it.

# vgchange -ay appvg

Mount the file system

# mkdir -p /appdata
# mount /dev/appvg/appdata /appdata

The file system is now available for use.


Labels: Linux, LVM, Quick HOWTO

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I'm Parthiban, An UNIX System Admin by Profession. I'm Experienced in Linux/Unix System Administration and Scripting. I have done lot of work on the infrastructure Mgmt side in Linux, UNIX and Windows system administration, Hardware, Storage and Data center. I'm blogging since 2008.
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4 Comments for "Moving volume group to another Server in Linux"

Hi Parthiban,
Nice article. Actually i need to move a Lun from one server to another. Hope this can help. Yet to test this. Will post you the feedback.
Thanks,
Prasan.

Thanks Parthiban for this article.
I've couple of queries to you.
1) As you said "not necessary to move disk drives from one server to another", then how can we export volumes from one host to another without moving the physical hdds ?

2) Later in the article, you mentioned that we need to physically remove the hdds (after shutdown) from old server and insert those into new server. My question is, whether we can export the volumes from old disks to new raw disks in the second server (without creating any partition)?
3) In reference to the question 2, whether this article suggests that we can use the same volume groups present in hdds of the first server by exporting it and importing it again in the another server (in the same hdds)?

Regards
ArunabH

Hi Arunabh,

Here is the answers to your questions.

1. In the article, I have specified that it is not necessary to use vgexport and vgimport. these commands only used to stop the activities on the VGs. So, Answer to your question is we cant move VG without moving physical disks.

2. You can use dd command to copy the data to new disks and then use pvscan, vgscan and lvscan to detect the LVM structure.

3. Yes. In this article, I have specified using same hdd's. This article just shows moving same disk from one server to another server.

Thanks
Parthiban

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