vgexport

[John_1005]

Could someone tell if vgexport -p -m -s would basically backup a volume group and its volumes? And could vgimport be used to restore a volume group? How is it different from a regular full backup? Also, what would be the best way to backup/restore specific directories in a volume? Thanks in advance.

[Steven E. Protter · Accepted solution]

vgexport backs up the volume group and logical volume information.

It does not back up the actual data as a full backup would do.

vgexport/import is used to save, recover and rebuild the information about the vg and logical volumes.

The process is not destructive and does not harm data. The data remains on the disk. The process does not back up the data in any way.

SEP

[Geoff Wild]

No - that is NOT a backup of data - all that does is create a map file of what the structure of the vg is...

Should be:

vgexport -p -s -v -m /tmp/vgXX.map

backup/restore - depends on your wallet - we use Veritas NetBackup.

Rgds...Geoff

[Pete Randall]

vgexport removes a vg from the system (unless run with the -p (preview) option, in which case it just goes through the motions and creates a map file) for the purpose of moving it to another system with vgimport. In no way could this be considered a backup.


Pete

[John_1005]

it just goes through the motions and creates a map file) for the purpose of moving it to another system with vgimport.


Could you please tell what this means? If it is not a backup, then what's the purpose of moving it to another system? Thanks

[Geoff Wild]

Say you want to mount the vg on a backup server - so that it backups locally to tape instead.

That's when you would do a vgexport/vgimport...

Also - in a clustered environment - to setup shared vg's.

Rgds...Geoff

[Steven E. Protter]

Yes Anand, but thats not a backup.

A backup implies copying the data OFF the disk. vgexport does NOt do that.

SEP

[John_1005]

Thanks everyone. Should the vgexport be done onto the tape?

[Steven E. Protter]

no

vgexport simply back up the volume group and lvm structure and removes the volume group.

data remains on disk and the disks can be imported to the same system or another system, depending on the cable/scsi setup.

vgexport will not create anything on tape.

Before you start

make_tape_recovery

That will back up the lvm/vg information to tape.

SEP

[Pete Randall]

I don't think you're getting the point here. There's no tape involved. When you run vgexport, it simply disconnects the VG from it's current system. All traces of the VG are removed and the VG is then available to be imported onto another system or back onto the same system.

In order to import it, you go through the following procedure:

mkdir /dev/vg01
mknod /dev/vg01/group c 64 0x010000
vgimport -s -m /tmp/vg01map /dev/vg01
vgchange -a y /dev/vg01

This assumes vg01 but it could be any VG.


Pete

[John_1005]

Sorry. Then, I think just

vgexport -p -s -v -m /tmp/vgXX.map

and save the map file in a safe place? I really donot need to export & import. I think the above command is sort of like metadata.

[Pete Randall]

Yes, with the -p (preview) option, it will save a map of the LVM configuration (or metadata in your terms) in the file you specify.


Pete

[renarios]

Hi Anand,

You can create a mapfile with vgexport, copy to another server and use the mapfile with vgimport to create a same vg there.
The command is being used for clustered servers connected to a storage area networks (SANs).
Don't just do some vgexport experiments, becuase you can throw away your vg configuration with that command too!
To get it visualized, try this presentation: http://docs.hp.com/en/144/app_consolidation.pdf

Cheers,

Renarios