Max Pv in VG

 
friki
Advisor

Max Pv in VG

Hi,

Can I change this in a Vg that already exists?
The problem is that I have a Vg that single admits 16 disks and I need add another. ¿It is possible or i have to create another vg with more disks and migrate information.?

thanks
8 REPLIES 8
Arunvijai_4
Honored Contributor

Re: Max Pv in VG

Take a look at these threads,

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=89846

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=619420

-Arun
"A ship in the harbor is safe, but that is not what ships are built for"
Jannik
Honored Contributor

Re: Max Pv in VG

nope but you could create a new vg and move the data. Then unmount and mount it at the location you want :-).
jaton
Mark Nieuwboer
Esteemed Contributor

Re: Max Pv in VG

Sorry it is not possible you have to create another vg and migrate the data.
when you create another vg make sure that you also use the -e and -s option to create a volume group that can take the biggest disk in your envirment.

good luck mark
Devender Khatana
Honored Contributor

Re: Max Pv in VG

Hi,

It is not possible. You need to recreate the VG. Also plan for other useful parameters properly before recreation. If you do not intend to implement the PVG strict allocation and plan to create simple file systems spread across one or more disks then you could actually do this migration very fast.

Suppose your VG has 16 disks. You intend to add another four.

On new 4 disks create a new vg with all appropriate and planned parameters to accomodate both more than 16 physical disks and more than current size disks.

Now create file systems one or two spread across these disks. Copy the data from the old VG to these file systems to spare some disks in the old VG. Now reduce old VG from the spare disks and extend new VG to them. Again create one or two file systems across these disks and move more data from old VG. Like this if you old and new disks are of same size in four go you should be able to complete the activity.
If the new disks are of big size then you shall be able to do this in less than 4 repeats.
If your VG has only one or two file systems then this will not be helpful.

But to be safe take one backup before this.

HTH,
Devender
Impossible itself mentions "I m possible"
Stuart Abramson
Trusted Contributor

Re: Max Pv in VG

Everybody is right. You can't change that on the fly. HP offers an "unsupported" tool called, I think, "vgtools" that does that, but I don't know where we got it. And you have to deactivate the VG to use it.

What we do is we just create another VG and put the new LVs in the 2nd VG. The Oracle DBAs don't care about VGs. They just care about LVs or Mount Points.
Mel Burslan
Honored Contributor

Re: Max Pv in VG

vgmodify utility is available by calling your HP account support manager. Success rate of using this command is very spotty at best. If you do not have much to lose by trying it, do it by all means. Buf if this is a critical situation, use caution and create a new vg with the right max pv in vg value and copy your existing data over to the new volumes. It means down time but it is much better than an unexpected data inconsistency down the road.
________________________________
UNIX because I majored in cryptology...
Raj D.
Honored Contributor

Re: Max Pv in VG

Hi Friki,

The MAX number of PV that can be in a VG is 255.

The default value is 16.

While the time of creating the vg you have to mention the Max no. of PV you are going to use ,
Ex: # vgcreate -p ...

Hope this will help,

Cheers,
Raj.
" If u think u can , If u think u cannot , - You are always Right . "
Matthew Ghofrani
Regular Advisor

Re: Max Pv in VG

Remember to use "-e" option (mentioned earlier) when creating your VG, like " -e 65535 ". Without this, VG would be locked into the biggest disk size at the time of creation & you won't be able to add bigger disks in the future. (well it would let you add bigger disks but won't let you use it!)

Matthew from Boston
Life is full of bugs