how to increase the Max PE per PV ?

[Carme Torca]

Hi,

I have the /dev/vg00 whith
Max PE per PV 4350
VGDA 6
PE Size (Mbytes) 4
could I increase the Max PE per PV... now I have to add another disk and I have this error:

vvgextend: Warning: Max_PE_per_PV for the volume group (4350) too small for this PV (17501).
Using only 4350 PEs from this physical volume.
Volume group "/dev/vg00" has been successfully extended.
Volume Group configuration for /dev/vg00 has been saved in /etc/lvmconf/vg00.conf


Thanks,
Carmen.
Max PE per PV 4350
VGDA 6
PE Size (Mbytes) 4

[Henk Geurts · Accepted solution]

hi Carme.

the only time the PE size can be set is when the vg is created ... :-(

the only way is to recreate the vg with the -s option
see man vgcreate


see also

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=792951
regards

[Indira Aramandla]

Hi Carmen,

"Could I increase the Max PE per PV... now" The answer is no.

The values Max PE per PV, PE Size, etc. are set at VG creation time. Once set, they can't be changed other than by recreating the VG.

The maximum number of physical extents is 65,535 as governed by 'max_pe' for 'vgcreate.

The maxiumum extent size is 256MB as governed by 'pe_size' during 'vgcreate'.

On 11.0, the maximum filesystem size is limited to 1TB. On 11.11 using version-3 or version-4 JFS you create a filesystem of 2TB, maximum.


IA

[Nguyen Anh Tien]

I think 'vgchange' command can not extend PE.
If you want to increate maxPE you must specify at creating time
#vgcreate -p "NUMber of PE" vg pv
that all
tienna
HTH

[Peter Unger]

what about vgmodify ? :D

[John Paine]

Peter,
Is that a Slovakian April Fools joke?
Cheers,
JP.

[Pete Randall]

Carmen,

Do you really need to increase the size of vg00? Couldn't you just add this disk as a new vg? The size of vg00 should remain relatively static as all it's supposed to contain is O/S related. After it's installed, the only real growth would be in log files which you should have a procedure in place to regularly trim anyway. It sounds to me like you've got business related data mixed in with your vg00. It would be much better to segregate the two and keep the business data in a separate vg.


Pete

[Bob_Vance]

How many current disks in vg00?
How big are they?
Size of new disk?
I.e., are you really wasting that much space?
E.g., adding a 36GB into a vg00 with 18GB disks wastes half of it, but if it's just a slightly bigger disk, maybe not so much.

OTOH, I agree with Pete.
What space are you actually trying to increase?
If you have a LVOL/directory being used for non-system stuff, you could (with the app down) copy it to the new vgxx, delete the old data, and mount the new on the old mount point (or make a symbolic link from the old dir to a new mount point).

You could do the similar thing with large system directories as well. E.g., /var/adm/sw/save (or /var/adm/sw/patches for 10x) can take up a lot of room if you've done a lot of patching. In the days of smaller disks (<18GB), I routinely made a directory in a large LVOL on another VG, copied the /var/adm/sw/save there, removed old /var/adm/sw/save, and then made a symlink to the new location.


Finally, if you absolutely want to increase the max PEs (without using vgmodify), you can use make_tape_recovery and rebuild your vg00.

E.g.,
make a couple of full backups of vg00, using fbackup or tar (if you're not using ACLs) and verify them -- this is major surgery, after all!!

## make_tape_recovery -p # preview

Then modify

/var/opt/ignite/recovery/latest/system_cfg

and change any of the vg00 attributes that you want:

volume_group "vg00" {
max_physical_extents=4328
max_logical_vols=255
max_physical_vols=16
physical_extent_size=4

You could also take this time to resize any LVOLs in vg00, as well.

Finish (resume) the make_tape_recovery to tape:

## make_tape_recovery -r -I -a ...

Then boot from the tape, recover the system.
You will have the new PE size.
Finally, restore the system from your full backup.


hth
bv

[Devender Khatana]

Hi Carmen,

All above are good in some sense. But what I really feel is that be adding a new disk of 17501 MB in your existing vg00 with MAX PE Per PV=4350, PE Size=4MB, you are going to effectively use 4350*4=17400MB out of 17501 MB of total space. I think this should be ok with you to use this as it is rather then following some of the advices given above.

Still to chnage any parameter or File System size etc. in vg00. Ignite backup is the best option.

HTH,
Devender

[Peter Unger]

John Paine: no vgmodify was not a kind of 1st april joke. it was a serious answer. it's an unsupported LVM hack. it's just rewrite the LVM structures on the PV. it'a not that hard to make that C code just LVM structure is needed.

you will never get it from HP neither from Veritas. It's really just a hack. But it works on 11i. haven't tested it on 11v2.

sollution for those which doesn't want to give up