Increasing VM guest volume group

[John Kelly_3]

I have a VM guest on a Host LV. I have increased the LV size on the host. How do I get the VM to detect the increased 'disk' size. The guest VG doesn't seem to see the change. The VG in question on the guest is not vg00.

I have tried vgexport/vgimport/vgchange.

Host and guest are on 11.23. HPVM 3.5. ia64.

[Torsten.]

Not sure if this works.

You can try with vgmodify on the guest, but I think the disk structure won't allow this (I did never try).

Better to assign another LVOL from the host to the guest and extend the guests VG and LVOLs.

[Steven E. Protter]

Shalom,

You may need to rebuild the VM.

I would suggest a process that would work would be:

ignite make_net_recovery

restore the image

Intervene at the interface that permits you on restore to change the logical volume sizes and such.

SEP

[Tim Nelson]

Read the Dynamic Lun Expansion here.
http://www.docs.hp.com/en/oshpux11iv2.html#LVM%20Volume%20Manager

vgmodify is great, NOT.

Less pain and suffering to either create a new larger backingstore and migrate data or just present a new lun to the guest and add it to the vg..

Your choice.

[Torsten.]

@Tim: The HPVM expert you are, did you ever tried this?

[Kapil Jha]

As torston said,its better to add a new lvol to guest and increase space at guest level.
the thing u did is most probably not possible.
BR,
Kapil+

[Tim Nelson]

I have.. It works. but... The risk of data loss scares me..

(Are you being condescending?)

[Torsten.]

I just wonder if it works or not ... as said, I never tried. The manual does not mention anything in this direction, so I assume it is really not recommended ... ;-)

[John Kelly_3]

Ok, so I'll back up everything on the VG and give vgmodify a shot.
@Tim, did you have to mess about with max_pe settings etc. when you did it? I'm a bit fuzzy on that level of technicality. I assume vgmodify will prevent me from over-writing data extents and will warn me if I need to free up the first extent with pvmove. Yes?

[Torsten.]

A bit off topic, but for all interested in:

HPVM v4.0

http://docs.hp.com/en/oshpux11iv3.html#HP%20Integrity%20Virtual%20Machines

[Tim Nelson · Accepted solution]

John,

I have used / tested this in the past with non critical data and it works as advertised. Did this 5-6 times in a VM environment. In my case I did this two ways, increased the physical LUN to the VMHost and also just increased the LV backingstore to the VMGuest.


When working with production data the risk becomes increased and I guess until I have do this 20-30 times I will still be scared of it.

If you read through the man page and doc referenced you can get an idea of what it is doing.

1) modify the vg meta data to change the limiting parameters. In this case max_pe.

2) add the additional mappings or reservations to the VGDA, typically this is created with the size neccessary to support the initial sizing. In most cases when you try to grow the VGDA is not big enough and wants to extend itself into the next extent ( 0 ). Typically extent 0 is used by data, you then have to move that data to the end ( if you have room ), then all the extents need to be renumbered so the 1st extent is back at the pole position.

That is alot of juggling around and if something errors "where did that data go ?", I am sure you can find it and fix it but by now we are wishing we would have just migrated to a new vg.

There was also a post just yesterday with someone working on this. His last comment was it worked !! ( but I lost data, that is ok, it was test data )..??

For me the jury is still out for the vgmodify functionality.

[Torsten.]

This was the thread:

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=1269993

But the happy end was a bit different ;-)

[John Kelly_3]

Thanks everyone. I'll let you know how I get on once I have the additional LUNs.

[John Kelly_3]

I finally decided there was no advantage in going through the disruption required to grow the existing VM VG with vgmodify. So I just added the new LUN into the VG on the host. Created another LV and added it to the VM guest using hpvmmodify. Then I could vgextend within the VM guest and extend the filesystems that way.
Thanks to all for the many contributions.

JohnK