How to restore LVs in a VG.

[Saneesh S]

Hi,
I'm facing a problem here.By mistake I exported a VG without any option so all the information regading the VG has gone .I recreated the group file with the same minor number.after that i used the vgscan command with -v and -a option ,so it has created the LVM tab entries.Now i can activate the VG as well as i can use vgdisplay command.In vgdisplay command it is showing the number of Current Lvs correctly.But it is not showing any LVs information it is showing only PVs in the vgdisplay -v command.It has not created any device files for the LVs in the /dev/vgn/ .I just want to know how to restore the LVs in that particular Vg.

Thnx in advance.
With Regards,
Saneesh S

[Noel Miranda]

Did you try
vgcfgrestore -n

This will get configuration information from the default configuration backup file
/etc/lvmconf/.conf

[Jdamian]

Instead "vgscan", I should have used "vgimport" command:

mkdir /dev/vgXXX
mknod /dev/vgXXX/group c 64 0xTT0000
vgimport -m /etc/lvmconf/vgXXX.mapfile disk1 [ disk2 ... ]

LVM saves vg configuration into /etc/lvmconf directory. This dir contains files ".mapfile" that contain the names of logical volumes.

[Hoang Minh Tuan]

Hi,

From your statement, it mean that you are lost LVM mapfile.
When you export without option, it will delete all of your vg and lv (but disk still CONTAIN your data) and lvmconfig (Volume Reverse Area and Logical Reverse Area).
If you use command lvmcfgrestore, it will destroy all of your LVM structure on disks and the result is may be lost data.Take care with that recommand.

YOu should only use vgimport -m mapfile_name(mapfile is create by vgexport before lately or it's in /etc/lvmconf/vg*.map). It will restore all your VG and LVS in VG structrure.

Hope it will solve your problem,
HMT

[Saneesh S]

Hello,

I tried vgimport as vgimport - m /etc/lvmconf/vg01.mapfile. but it is giving an error saying that entry already exists in the /etc/lvmtab file and import failed.

Regards,
Saneesh S

[Thayanidhi]

Hi,

Posibly you need to redo the same thing again. Upto my knowledge if you have not saved the map file previously, you don't find the map file /etc/lvmconf
In this folder you find only configuration backups (not maps). It doesn't matter.

Now save the map files for all other Vg's (vgexport with preview option) for safety.
vgexport the improper VG. Then run vgscan.
Now create vg folder and group file.Then run vgimport . This will create all lv device files. Only problem here would be you will loose all your custom names for lvs. You find all lvs as lvol1, lvol2 ..etc. then mount and find out actual content.

Hope this helps.

Regards

TT

[Rita C Workman]

Hmm..take a look at lvmtab (strings /etc/lvmtab). Is the vg there? If it still is and you ran the vgexport than move the lvmtab file to lvmtab.old and run vgscan.
Redo the vgimport again from the mapfile you just tried to use. See if that helps.

Also, yes it will create default lvnames, BUT, you can maybe fix that ! Once you have run your import do a cat on /etc/lvmconf/vgmapfile and you'll see the default names. Have you tried just editing the file and changing the lvols back to what they used to be. Activate the vg and take a look. I did this once and it worked.

Just a thought,
Rita

[Hoang Minh Tuan]

Saneesh,

Your problem is it had vg in lvmtab file so that it will not restore vg which existed in lvmtab.
The best way is check vg01.map (be careful between vg01.conf and vg01.map). May be vg01.map is in /tmp or other filesystems, please check it. Cat vg01.map to show number of lvs and lv name is correct to vg01 you had exported.Then do following:
vgexport /dev/vg01 (it automatically delete vg01 entry in lvmtab)
mkdir /dev/vg01
mknod /dev/vg01/group -c 64 0x010000
vgimport -m /etc/lvmtab/vg01.map

Hope this help,
HMT