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Extend existing physical volume

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Carlos A. Munoz Lopez
Frequent Advisor

Extend existing physical volume

Hi guys. I have an Integrity server running HP-UX 11.23 connected to an EVA 4000. There's a volume group formed by a single 15GB physical volume and I want to extend it. On EVA, I pretend to extend the LUN from 15GB to 30GB by modifying the requested capacity. What do I have to do so HP-UX recognizes the new LUN size so I can later extend the volume group? I don't want to create and additional vdisk, I want to use the existing one. Is there any way possible so I can achieve this?
Honored Contributor

Re: Extend existing physical volume

No you can't extend a LUN on the backend storage array and make it visibly bigger to HP-UX. That is not supported.

~hope it helps
A. Clay Stephenson
Acclaimed Contributor

Re: Extend existing physical volume

If you were under 11.31, you would have vgmodify but under 11.23 the only official way is to backup your data, vgexport, and recreate the VG. It's much simpler (and supported) to add a 2nd 15GiB LUN to your existing volume group. There is really no downside to adding a 2nd PV to the VG and it can be done "on the fly".
If it ain't broke, I can fix that.
Ivan Ferreira
Honored Contributor

Re: Extend existing physical volume

>>> don't want to create and additional vdisk, I want to use the existing one.

Considering the limitations, is there an special reason for this?
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Carlos A. Munoz Lopez
Frequent Advisor

Re: Extend existing physical volume

Thank you for all your answers. Well, there's no limitations on creating an additional vdisk. It was only a doubt that I had in mind, and I just wanted to know if there was any possibility to do it. Thank you again, I appreciate your comments.
Valued Contributor

Re: Extend existing physical volume

The vgmodify command which is available for HP-UX 11i V2 if you install the LVM patches PHCO_35524 and PHKL_36244.

Refer to the following Technical Knowledge Base document for specific information about the vgmodify command and Max PE per PV -


Re: Extend existing physical volume

HI i am new in HP unix, but the simmilar issue i am facing, i have 100gb of disk and 50gb of PV is created on it and same as 50gb VG is created on it now i want to extend the VG size. how can i do it.

Honored Contributor

Re: Extend existing physical volume

Sandeepbsc25, you should have opened your own thread (with the "New Post" button at the top of the thread list view) instead of continuing an old thread. And you should provide some basic information:

  1. the HP-UX version you're using (run "uname -a")
  2. the "vgdisplay -v" information of the VG you're planning to extend.

The HP-UX version will determine if the "vgmodify" command is available or not.

The "vgdisplay -v" output will help us give you the exact commands you'll need, and it will allow us to check several important parameters of the VG.


If the "Max PE per PV" and "PE size" parameters are big enough to handle a 100 GB disk, all you need is to make the LVM aware of the increased PV size. Run "man vgmodify" and read the parts with title "Reconfigure a VG to account for Dynamic LUN Expansion".


If the value of (Max PE per PV * PE size) is less than 100gb, you'll have to unmount & deactivate the VG and then use vgmodify to increase the "Max PE per PV" value. In this case, run "man vgmodify" and read all of it.

The "PE size" parameter is selected at VG creation time, and cannot be modified after that.


If your HP-UX is older than 11.31, it may not have the vgmodify command. If the HP-UX version is 11.23, you can get vgmodify by installing some patches. If it is 11.11 or older, you may have to backup the data in the VG, then destroy the VG and re-create it with bigger parameter values, and restore the data. If you'll need to do this, make sure you won't have to do it ever again for this VG: choose the parameters so that the VG can take even more/bigger PVs in the future, if necessary.