topic lvextend on shared vg in Operating System - HP-UX

lvextend on shared vg

Rui Marreiros — Mon, 21 Jan 2002 17:05:57 GMT

does anybody knows if, with the latest LVM versions&patches, is it possible to extend a logical volume on a shared vg.
The goal is to precreate a few lv??s with only one PE and when oracle OPS will need a new datafile I??ll extend the lv to the desired size and use it as a new datafile.

Re: lvextend on shared vg

James R. Ferguson — Mon, 21 Jan 2002 17:29:31 GMT

Hi:

Yes, this should work. Assuming that the logical volume has been declared appropriately to the package control scripts, and that the volume group has been made known to all MC/ServiceGuard nodes, then when the logical volume is mounted, the new size will be deduced. That is, you can 'lvextend' (and 'extendfs' or 'fsadm' appropriately the filesystem) on your primary node.

Regards!

...JRF...

Re: lvextend on shared vg

Rui Marreiros — Mon, 21 Jan 2002 18:04:02 GMT

let me clarify on what I pretend to do:
Oracle Parallel Server implies that I use raw-device data-files, i. e., the lv??s on the shared vg are not mounted. Oracle allows , as you problably know to write directly to the raw device files. But on the other hand if you want to create a new lv ( to use as a new data-file) all the nodes in the cluster must be aware of it so after the creation you need to export( in one) and then import the vg in all the other nodes, and to do this you must de-activacte the vg which implies down-time to the database.
If I could extend a lv in the shared vg will all the nodes be aware of it ? If not ,this will not work.
the procedure would be like this:
after creating the vg , some lv??s , with say 10 M each , and doing
vgchange -S y -c y /dev/vgops
vgchange -a s vgops
lvextend -L 1000 /dev/vgops/lvol1

will I see this ?
node1 > lvdisplay /dev/vgops/lvol1
..
..
LV Size (MBytes) 1000
..
..
node2 > lvdisplay /dev/vgops/lvol1
..
..
LV Size (MBytes) 1000
..
..
???????
The thing is that I can??t try it since I??ve no
T&D cluster.
thanks in advance

Re: lvextend on shared vg

melvyn burnard — Mon, 21 Jan 2002 18:11:09 GMT

There should be no problem doing this, as extending an LV just changes the LVM info for the LV size on the discs in the VG. As the VG gets activated on one of the nodes, this will enable the LVM code to read the sizes for each LV from the discs.
As you will already have created and shared the VG/LV's etc, ther eshoulde be no more to do.

HTH

Re: lvextend on shared vg

Rui Marreiros — Mon, 21 Jan 2002 18:44:23 GMT

I??m only worried with this excert of the on-line hp-ux manual:

http://docs.hp.com/hpux/onlinedocs/B2355-90691/00/00/4-con.html

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

Would the latest versions support it ?

or at least will it work ?

by the way I was not clear enough in the last message, obviously the vg -a y is performed in all the nodes inthe cluster

thanks in advance

Re: lvextend on shared vg

melvyn burnard — Mon, 21 Jan 2002 18:46:50 GMT

Ah, missed th efact this was actually SG OPS Edition.
If this is the case and the VG's are activated in shared mode, vgchange -a s mode, then the simple answer is no, you cannot lvextend the lv's while the VG is activated.
sorry for the misunderstanding.