Dynamic lun expansion LVMv2 (no vgmodify)

[Emil Velez]

I have looked at all of the documentation and have seen the vgmodify white paper.

That is great for LVMv1 but how do we do dynamic lun expansion with LVMv2 without the vgmodify command

A cookbook example would be appreciated.

I know that vgmodify is not needed for the max sizes of disks or max disks in a volume group but it seems that the dynamic lun expansion feature is somewhat hidden.

Thanks for anything that is provided (+points)

[Torsten.]

Hi Emil,

vgmodify is for LVMv1 only.

My understanding is that LVMv2.x will do this automagically, as long as all the value limits are set high enough. I did not test this yet.

See also

http://docs.hp.com/en/oshpux11iv3.html#LVM%20Volume%20Manager

http://docs.hp.com/en/5992-4589/index.html

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01941067/c01941067.pdf (BSC link updated by admin)

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01919369/c01919369.pdf (BSC link updated by admin)

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01919368/c01919368.pdf (BSC link updated by admin)

[Emil Velez]

Thanks for the reply..

I read all of the documents referenced and that is why I am asking the question.



I see no reference in LVMv2 documentation to resizing luns and that is the subject of the question.

Even if it done automatically it should mention when it happens and there must be some limitations.

[melvyn burnard]

The online Lun expansin is outside of the Volume Management side, so this occurs for any LUN.
You would still need to use lvextend and extendfs for LVM2 as far as I am aware

[Emil Velez]

I realize that extending the lun is done at the disk array level. But with LVMv2 How do I let it recognize the extended size of the lun.

With LVMv1 I use the vgmodify command to recognize the extra size of the lun.

With LVMv2 what do I do once I resized the lun ?

[Bernhard Mueller]

Emil,

I would assume first thing is you need to execute some command that sends a scsi inquiry command to obtain the new lun size and let the OS know about it.

This would typically be "ioscan -fnCdisk"
- not sure if "diskinfo " would be sufficient.

Regards
Bernhard

[Emil Velez]

Of course but I am asking how LVMv2 recognizes the new size. Vgmodify does that for LVMv1

[smatador]

Hi Emil,
I have the same discussion with my customer.
But in the vgmodify_wp.pdf, the wp said on page 53 that
in review mode, you do
vgmodify â r â a â E
and finally
vgmodify â a â E
Does it mean that the vgmodify wp is refreshed?
Do you have test this solution until february?
Unfortunately, I can't test for the moment.

For all member, does anybody have test the online DFC to decrease ?
Thanks

[Emil Velez]

vgmodify is now on lvmv2