Is there anyway to modify the max_pe setting on a VG?

[Frank Delorey_1]

We migrate systems from small disk drives to larger
drives on a regular basis. For example vg01 contains 4 4G drives and we want to
migrate the data to 9G drives without destroying and recreating the vg01 volume
group. I know that there is not a supported way to do this but is there a trick
somebody has found so that a
4G drive can just be replaced with a 9G drive?

Thank You,

Frank DeLorey

[Steve White_8]

The max P.E. value gets set when you run vgcreate. The only method I know of
changing it is by creating a new volume group. You could try exporting the
volume group, then create it with your bigger drive, this will change you max
P.E.

Then you could import the drives that got dumped when you did the export.

[Dan Hull]

There is simply no way to modify the maxPE/PV setting once the VG is created
(including "tricks") because it would involve modifying the entire header and
allocation structure of the VG!

Also, you cannot "import" disks into a VG that already exists. You can extend
them into a VG, but none of the data on them will be retained, since you have
to pvcreate them first.

Probably the best way of approaching this problem is:

Create a new VG with the 9G disk(s) called something like "vgtemp", including
lvols of the same name as on vg01. Move all the data from vg01 to the new VG,
then export vg01 to remove it from the system.

vgexport vgtemp from the system. Then, using SAM, import vgtemp back into the
system, but call it VG01.

Finally, after verifying everything works, pvcreate -f the old 4G disks and do
whatever you want with them.

NOTE: You can set the MaxPE/PV when you do the vgcreate, so you might consider
setting it to 18G when you create vgtemp. That way you won't have this problem
next time you want to buy bigger disks :)