vgmodify

[Rudy Montemayor]

Does any body have any experience(s) good or bad on how well this HP unsupported tool works? This would be used for example to modify the Max PV parameter of a volume group w/o having to reconstruct it from scratch with a vgcreate. I have several volume groups in which I need to increase the Max PV and this tool would save a lot of time and effort if it does the trick. Thanks.

Rudy

[Alex Lavrov.]

Hey, I wouldn't use something that is not supported by HP, because you can harm your system and HP will not be able to help you.

You can also refer to this thread:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=213293


Regards,
Alex.

[RolandH]

Why so fearful?

What ist the supported way?
1. Backup Data
2. Recreate VG
3. Recover Data ( takes the most time )

What can be your way?!
1. Backup Data
2. vgmodify
Does it work ? NO ! Go on with supported way.

So if it will not work you can go on with the supported way.
Nothing to lose.

And you can test it first.
Create a vg with MAX_PV value of 1 and try to modify it with vgmodify. If it works try to add a disk to that vg.

Roland

[Rudy Montemayor]

Alex and Roland, both of you make valid points. Any time you are going to try something new/unsupported you better have a complete backup of you data. With more testing to be done I think I would follow Roland's approach.

One other item guys that I want to understand is that using vgmodify will work to increase Max PV as long as you do not go over your pe_size limit for the VG header table(s). If I try to go over 141 for my Max PV for example in my scenario I get the message that the VGRA (Volume Group Reserve Area) would be to big for my 4 MB extent size. So it appears that this tool is limited in what it can do which is OK and I would have to use vgcreate if I want to go past the 141 Max PV and increase my pe_size to 8MB. Thanks.

Rudy

[Hans Hendriks_1]

Rudy, simple question: do you have this tool?

I would like to extend my vg's with disks far larger than the first one and now I'm running into the max PE limit.

thx

[Devender Khatana]

Hi,

Allthough I have never used this tool but you need to take some precautions while using this. Importantly the parameters should be modifed in relevance to the other present parameters which you are not going to touch or for that matter can not even touch.

There is a relation is max_pe_per_pv and PE_size parameters, max_pe_per_pv will also effect this but not that much. So do not increase max_pe_per_pv to a very large value which you will hardly use in future and just want to increase it as preventive measure for avoiding use of vgmodify in future. Doing this can cause some errors and I am not sure if there is some rollback option available.

Always follow a lay man advice "backup is muct before change".

Also do keep the results posted.

HTH,
Devender