Difference between vgexport/vgimport and vgcfgbackup/restore

[Franky_1]

Hi together,

can you explain to me what's the "big" difference between vgexport/vgimport and vgcfgbackup/vgcfgrestore respectively when to use the one and when to use the other ?
Somehow it doesn't seem quite clear to me

Thx in advance

Franky

[bhavin asokan]

hi,


The vgcfgrestore command restores the LVM configuration data from a default (-n option) or alternate (-f option) configuration backup file to the physical volume named by pv_path.it restores the vg information on disk(like VGRA ).

vgexport/vgimport is just adding/removing the entry of VG in the lvmtab file and creates LVs in the respective VG.it is not changing any data in the disk(PV)
regds,

[melvyn burnard]

vgcfgbackup/vgcfgrestore is used to back up LVM info from the physical disks to a file on the system, which can then be used to rewrite that information onto a new replacement disk upon failure of an exisitng disk. It does not change the VG information, or touch /etc/lvmtab etc.

vgexport/import will remove the definitions of a VG from a system including removuing it from /etc/lvmtab, unless used with -p option, and vgimport is used to import the vg definitions onto a system..
Refer to the man pages for more information and details.

[Bharat Katkar]

HI Franky,
Just to add something more:

1. vgexport/vgimport plays around with the VG configuration stored on the server itself whereas vgcfgrestore/backup play with the configuration which is there on the disk (PV's)

2. vgexport/import is is basically used to copy the VG structure from one server to another server which is required in HA cluster whereas the vgcfgrestore/backup is used to backup the Metadata stored on the PV's and restored incase of bad disk or disk replacement.

3. vgexport is also used to delete VG's

4. vgexport/import is used for replicating configuration whereas vgcfgrestore/backup is done for recovering from failures.

Hope that helps.
Regards,

[Muthukumar_5]

vgimport / vgexport are used to make configuration on physical disk's volume groups there without modifying logical volume informations there. vgimport is combining the actions of creating new volume group with vgcreate to update the volume groups. vgexport used to delete existing volume groups

vgimport / vgexport can work on shared mode on cluster systems.

vgcfgbackup /vgcfgrestore are used to take backup of VG configuartion informations into a file / restore or list the VG informations again. It will not do any action on physical disk or volume group configurion file.

vgcfgrestore cannot be performed if the volume group is activated in shared mode.

Differences are physical volume group settings configuration and updation and volume group configuration file configuration and restoration.

[Franky_1]

Hi,

if i understand correctly then in case of desaster recovery you'll need both (vgexport and vgcfgbackup) to restore a disk from scratch - vgcfgbackup for the LVM Structures on the disk itself and vgimport for the VG's on the system (lvmtab)
Is that right ?

Thx

Franky

[Geoff Wild]

Depends on disaster - if server - then vgimport will work if you have map files.

If disks, then vgcfgrestore.

Rgds...Geoff

[Kent Ostby]

If I am dealing with a situation where there seems to be some sort of problem on a boot disk or with disk activation, I will try the vgcfgrestore first.

This quite often works.

If that still hasnt worked then I will try the vgexport/vgimport.

Best regards,

Kent M. Ostby