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MC/Service Guard and Online JFS

 
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Damien Lass
Advisor

MC/Service Guard and Online JFS

All-

I want to extend a filesystem online that is a part of a MC/Service Guard package. I have Online JFS installed on my HP-UX 11.00 system(s). The 'man' page for 'lvextend' states that is does not work on a logical volume in shared mode. What does this mean? Is this the same as a volume group being cluster aware or activated in exclusive mode? Can I do this online on a MC/ServiceGuarded logical volume without disturbing the package? If so, how?

Any help would be appreciated!
5 REPLIES 5
John Poff
Honored Contributor

Re: MC/Service Guard and Online JFS

Hi,

If you are working on a VG in ServiceGuard, the VG will be activated in exclusive mode. You can lvextend it with no problem. It shouldn't bother the package.

I think the shared mode is a funky mode for a VG that is used on two different systems at the same time. I did that by acccident on a box once and I don't really want to talk about it! ;)

JP
Ashwani Kashyap
Honored Contributor
Solution

Re: MC/Service Guard and Online JFS

Yes , you can do this online . In an SG environment the VG is activated in exclusive read write mode . So an lvextend can be performed . If the VG has been activated with -s option ( shareable read write , like in OPS )then its problem .
Assuming you are not running OPS , you can increase the file system online .

DO an lvextend to extend the logical volume .
DO an fsadm so that the file system is aware of the extra space .

And thats it .

Remember if u r adding an extra PV to the VG for your lvextend , then u will have to export the VG and import it back on the adoptive nodes . But if you VG has enough space , then u just have to perform lvextend and fsadm provided you have online JFS .
Michael Elleby III_1
Trusted Contributor

Re: MC/Service Guard and Online JFS

Well because you are talking about lv configuration, I have always been wary about performing lvm tasks while the package that the lv exists in is running. (Although I have done lv moves to different disks whilst the package was running)

One main reason, the vg config needs to exist on the other node for failover reasons, so I would shy away from doing it while the package is running.

The easiest way to handle it:

Halt the package (this will umount the lv)
vgchange -a n (deactivate the vg)
vgchange -c n (remove cluster mark)
vgchange -a y (activate the vg)
Make your changes to the LV
Do your vgcfgbackup to create a new map file
distribute to other node(s) in cluster
vgchange -a n (deactivate vg again)
vgchange -c y (set cluster mark)
Restart the package

Others may have more viable solutions, but this is just a suggestion..

HTH,

Mike-
Knowledge Is Power
Damien Lass
Advisor

Re: MC/Service Guard and Online JFS

John (or anybody else!)-

If I extend a filesystem in MC/ServiceGuard, I DO NOT have to export the mapfile from the primary node to the other nodes correct? The mapfile does not hold the size of the logical volume, only the disk information (ctd #s and lv names) correct?

Thanks again!
John Poff
Honored Contributor

Re: MC/Service Guard and Online JFS

You are correct. If you just increase the size of an existing logical volume you don't have to vgexport the map file and vgimport it on the other node, because the other node already knows about the logical volume and doesn't really care what size it is until it is ready to mount it. As others have mentioned, if you add a PV or a new LV you'll have to do the vgexport/vgimport dance. I appreciate the caution that some people use with running packages, but I can tell you that I have done LVM work on running packages dozens of times and haven't had any problems.

JP