Adding disks to existing LVs in a HA enviroment

[Rob Sletten]

Greetings,

I recently added 5 EMC disks to existing LVs in a volume group on box 2 of a HA cluster running MC/SG. I didn't create any new LVs, just simply added 5 new disks to the VG and then lvextended to the new ones.

I then did the usual vgexport -p -s -m /tmp/vg03.map vg00 and ftped it to the 1 box and tried to import it but failed for some reason I forget. Of course that VG isn't activated on the 1 box because 2 is currently running it (where I added the disks).

My question is this. The /etc/lvmtab on the 1 box does not reflect the 5 (actually 10 because of the alternate links) new disks. When I fail the package and that volume group over to the 1 box, will /etc/lvmtab update itself?

If not, whats the procedure I have to do to update /etc/lvmtab on the 1 box?

I've taken a look at the mapfile created with the vgexport command and it doesn't contain device names, only logical volumes. The device paths to the shared disks are different on the 1 and 2 systems although it's easy to figure out whats what (only the controller number) is different. Is there any issue with that?

Thanks for any info!

Rob

[John Poff]

Hi Rob,

Your /etc/lvmtab on box 1 won't fix itself (although that would be cool - I would have fewer gray hairs if it did!). You'll need to get the vgimport done to make it happy. Box 1 won't be able to use that VG until you get it fixed.

When you look at the map file, the first line is the VGID entry. The vgimport command looks at all the disks and imports any of them that have that VGID.

If you'll try the vgimport command on box 1 again and post the errors, maybe we can figure out what is going on.

JP

[John Poff]

I missed your last question. You are right. As long as the systems are seeing the same disks, it doesn't matter that the controller numbers are different. Some people like to try to make them be the same to simplify things, but as long as you have a handle on what is what, it doesn't matter. The best tool I have found for keeping up with that is the EMC 'inq' utility. With the '-et' options, it will tell you which port each controller is plugged into on your EMC.

JP

[Rob Sletten]

Thanks John for your great information. Does the VG need to be inactive (not mounted) on the 2nd system before you do the vgimport on the 1st system? Does it need to be activated on the 1st system?

Thanks!

Rob

[George A Bodnar]

You don't have to have the VG deactivated, but you do need to export from the backup box before attempting the import. You can't import over something that was already imported.

[John Poff]

Rob,

The vg needs to be active on the system (box 2) where you are running the vgexport. On the first system, you'll need to vgexport the vg, mkdir your /dev/vg03 directory (it gets nuked by the vgexport), mknod your group file, and then do your vgimport. Be sure to do an 'ls -l /dev/vg03' on box 1 to make sure you get the right minor number for the group file. Of course, it should be the same as the minor number for the group file on box 2.

JP

[Ashwani Kashyap]

No your lvmtab won't fix by itself .

Make sure you see the 5 new disks on box1 . On box 2 where the VG is active , export the VG is shared and preview mode in a map file . This map file will only have the VGID and LV names .

Copy this map file to box 1 .
The VG that you want to import should be in a deactivated atate here . Now export the VG using vgexport /dev/

Now mkdir /dev/
#mknod group c 64 0Xyy0000
yy should be the same number as it is on your box 2 .

Now do vgimport
#vgimport -s -m /dev/

Once this is successfull , you can see the new disks in your lvmtab .