No enough PE per PV

[dev44]

I need to add a 400GB LUN to the volume group. I don't have enough PEs. I am going to reduce the Max PV, but was wondering how to figure out what to reduce it to. I figure if I reduce it to 20 or 30, I should have enough but is there a way to calculate what I can bring it down to and still have my Max PV as high as possible?

Thanks,

[Torsten.]

Can you post a "vgdisplay -v" for this VG?

[Duncan Edmonstone]

Are you talking about using vgmodify to change the max per per pv in a VG? Od so there's a sort of preview option which shows you possible configurations - I think its 'vgmodify -t '.

See this whitepaper for details:

http://h20000.www2.hp.com/bc/docs/support/SupportManual/c01920387/c01920387.pdf (BSC link updated by admin)

Or are you talking about something else?

HTH

Duncan

[James R. Ferguson]

Hi:

If you are running 11.23 or 11.31, then Duncan's link to 'vgmodify' and/or the 11.31 manpages will enable you to calculate a value.

If you are running 11.11 (or earlier) see Technical Knowledge Base # emr_na-c01037913

There in are tables of maximum max_pe values for various disk configurations.

Regards!

...JRF...

[dev44]

Sorry, I completely forgot to add the vgdisplay:VG Name /dev/vgXX
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 29
Open LV 29
Max PV 144
Cur PV 4
Act PV 4
Max PE per PV 14076
VGDA 8
PE Size (Mbytes) 16
Total PE 41907
Alloc PE 40219
Free PE 1688
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

I do plan on using vgmodify.

[Torsten.]

Still not sure about your OS version (uname -a)?

I wonder about this:

Max PV 144
Cur PV 4


Do you really plan to add 140 disks to this VG?

[dev44]

HP-UX 11.23

No we don't plan on 144 disks....but I would like to figure out/calculate how many free PEs I would have if I brought that number down to say 20 or 30.

[Rasheed Tamton · Accepted solution]

Your real issue is that your Max PE per PV (14076). The PE Size is 16 MB. So you can only use a LUN size of 220GB (14076*16=225216), even if you present a 400GB LUN to the system.

So, you need to modify the Max PE per PV to 25600 (25600*16=409600) in order to use a 400GB LUN. In future, if there is a requirement for higher size LUNs, then increae Max number of PEs to yet higher value (32000 for 500GB LUN).

man vgmodify (read it carefully)

Regards.

[Torsten.]

Maybe I don't understand ... but MAXPV and FREEPE is not directly related.

PV physical volume (= disk or LUN)

Max PV 144
Cur PV 4

Now you have 4 disks (LUNs)

Max PE per PV 14076
PE Size (Mbytes) 16

Total PE 41907

You have a total of 670GB.

Alloc PE 40219
Free PE 1688

27GB are still free and unassigned.

[dev44]

HP-UX 11.23

No we don't plan on 144 disks....but I would like to figure out/calculate how many free PEs I would have if I brought that number down to say 20 or 30.

Sorry if I take a long time to respond but I am getting errors every time I post, that's if it posts at all! Very frustrating.....