Logical Volume creation while MC Serviceguard is running

[Leoanrdo Bowens]

I have a MC Serviceguard cluster and packages currently running. My question: Can I create a logical volume from an existing volume group that is running in the cluster and mount it without it affecting the system or it's current configurations? Or do I have to halt the package, cluster and deactivate the volume group from the cluster and then create the lvol and then add the volume group back to the cluster and add the new lvol to the .cntl etc?

[Bryan D. Quinn]

Hello,

I beleive you can just add a logical volume without a problem using standard LVM, that is it will not be part of the cluster. Say for a temporary Lvol. Now if you want it to be permanent or a part of the cluster it would be more in depth and require changes to the cluster configuration.

-Bryan

[Uday_S_Ankolekar]

You can create Lvol and make it part of the Service guard while package/cluster is running and re-import the VG on the other node also don't forget to update the package ascii file.

Goodluck,
-USA..

[Bryan D. Quinn]

Hello again,

Attached is the procedure that we use for adding a VG to an MCSG cluster. I beleive if you pick up with the lvcreate command it should work just fine. I beleive these changes can be made with the cluster up and running, but we are very conservative here and do it with everything down.

-Bryan

[John Poff]

Hi,

You can add a logical volume with the cluster and packages running. I've done it a bunch of times. Just be sure to add an entry for the new LV/filesystem in your package control file, and push the control file to any other nodes that need it. As mentioned, you'll also need to do a vgexport on the node you add the LV to, creating a map file and copying it to the other nodes where you'll need to do a vgimport to pick up the new lvol that you added. Otherwise the other nodes won't know about it and you'll get a nasty suprise the next time you try to failover. Oops! Done that more than once also. :)

JP

[Leoanrdo Bowens]

Thanks for all of expert answers. You all have been a tremendous help. Have a great day.

[Leoanrdo Bowens]

Thanks for all of the expert answers. You all have been a tremendous help. Have a great day.

[Tim D Fulford · Accepted solution]

The above stuff is the standard... I have a slightly different method. I do NOT like the vgexport/vgimport method as, espeecially using vgexport -s -p -m , the import will interupt the disks. This causes a temporay interuption to service & I get complaints.

What I tend to do is

1 - create the LVs normally using lvcreate
2 - edit the /etc/cmcluster//.sh file appropriately
3 - note the minor number of the new lvol
4a - on the stand-by/other systems do
mknod /dev//r c 64
mknod /dev// b 64
4b - Alternatively tar cvf - /dev/ | remsh tar xvf -

The above has one drawback that I believe still exists with the vgexport & vgimport methods. It is a good idea to do a vgchange -a r & then vgcfgbackup

Regards

Tim

[Tim D Fulford]

The above stuff is the standard... I have a slightly different method. I do NOT like the vgexport/vgimport method as, espeecially using vgexport -s -p -m , the import will interupt the disks. This causes a temporay interuption to service & I get complaints.

What I tend to do is

1 - create the LVs normally using lvcreate
2 - edit the /etc/cmcluster//.sh file appropriately
3 - note the minor number of the new lvol
4a - on the stand-by/other systems do
mknod /dev//r c 64
mknod /dev// b 64
4b - Alternatively tar cvf - /dev/ | remsh tar xvf -

The above has one drawback that I believe still exists with the vgexport & vgimport methods. It is a good idea to do a vgchange -a r & then vgcfgbackup & lastly vgchange -a n

Regards

Tim