Max_PE_per_PV

 
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Tina Stevnhoved
Occasional Contributor

Max_PE_per_PV

Hi,

Sometimes when I add a disk to a existing VG, I got the warning tha the Max_PE_per_PV is too small. Then I can only use a part of the physical disk.

Is it possible to change Max PE on a existing VG?

Regards

Tina Stevnhoved
WM-DATA
email: tiste@wmdata.com
9 REPLIES 9
Pete Randall
Outstanding Contributor

Re: Max_PE_per_PV

Tina,

Sorry, no. The Max PE setting is done at vgcreate.


Pete



Pete
Bill Hassell
Honored Contributor
Solution

Re: Max_PE_per_PV

This is a limit imposed by vgcreate and is very often set much too small. Since the space allocated for the PE table is at the front of the disk, it is not possible to make it larger. You'll have to backup all the data, delete and re-create the volume group. In case this is a growing application, make the max PE limit higher than you need right now. If this is a several hundred Gb volume, you may need to increase the PE size from 4Mb to something larger as the maximum number of PE's cannot exceed 65,535.


Bill Hassell, sysadmin
Massimo Bianchi
Honored Contributor

Re: Max_PE_per_PV

Hi,
the simple answer is, unfortunatly, NO.

You define this parameter when you create the vg, with a combination of the "-s, -l, -e" options.

I suggest you to create a new vg, with the appropriate parameter, put the new and big disk there, an plan how to move your old app to this new vg.

If it is vg00, you may even think of a fresh re-install, with the make_tape_recovery.

HTH,
Massimo
Enrico P.
Honored Contributor

Re: Max_PE_per_PV

Hi,
max_PE an option of the vgcreate command.
You can backup data in vg, export vg, recreate your VG with disk having max dimension first and next add the other disk, reimport data.

Enrico.
Michael Steele_2
Honored Contributor

Re: Max_PE_per_PV

Hooo, this is not good:

"...Sometimes when I add a disk to a existing VG...then I can only use apart of the disk..."

If you've been adding different size disks into one vg then determine which disk is largest and recreate the entire vg using the largest first.

Default MAX_PE = 1016 and PE_SIZE = 4 mb.

Example:

vgcreate -e 40000 -s 8 /dev/vg## /dev/dsk/cXtYdZ
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twang
Honored Contributor

Re: Max_PE_per_PV

The Max_PE_per_PV only changeable at creation time of the VG. So you need to recreate the VG. I would suggest use ignite to help you to recreate the VG.
T G Manikandan
Honored Contributor

Re: Max_PE_per_PV

That cannot be done without re-creating the VG.
check for the man pages of vgcreate(1M)
Geoff Wild
Honored Contributor

Re: Max_PE_per_PV

As the others have said, you will have to create new volume groups (or copy/backup your data - then vgexport the volume group(s), then re-create them with larger MAX_PE).

If you are going for new vg's, then also check the kernel parameter MAXVGS - make sure it is large enough to accomodate your needs.


For say a 32GB LUN - set PE Size to 8 (Mbytes) to say 4315. Also, if you need a lot of disk in your vg, bump up the MAX PV - -p with vgcreate.

Rgds...Geoff


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Tim D Fulford
Honored Contributor

Re: Max_PE_per_PV

Going one step on... Watch out for MAX LV per VG!!! it is 255 & a hard limit. We hit it and so can only use 510GB of a 800GB VG... oops (Informix uses max chunk size of 2GB! how quaint)

Tim
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