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Re: PE and LE

 
Johnson Punniyalingam
Honored Contributor

Re: PE and LE

Yes , You are Right, Congratulations into moving to LVM ..:)

But did you read the "Documents or PDF files" which >>Matti<< Gave you ? -> Hence you are beginner you must read & understand the documents ,

vgmodify -> can be used only in HPUX 11.31 version if you are running below than,
you need remove the Volume Group and recreate Volume Group inorder to adjust.
Problems are common to all, but attitude makes the difference
Kranti Mahmud
Honored Contributor

Re: PE and LE

Hi newunix,

as a fresh unix user, u shud have good knowledge on LVM. The attached doc will help U.

Rgds-Kranti
Dont look BACK as U will miss something INFRONT!
Michael Steele_2
Honored Contributor

Re: PE and LE

Hi

Yep, you can with 11.31, else he's right. What's your version?

11.31
vgmodify -e # -s # /dev/vg /dev/dsk/c...

Below 11.31
vgcreate a new vg. This means you've got to acquire new luns, create the new vg and copy old vg to new vg.

Open up a new thread if the later.
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Matti_Kurkela
Honored Contributor

Re: PE and LE

Your vgdisplay output said:

>Max LV 255
>Cur LV 1
>Open LV 1
>Max PV 16
>Cur PV 1
>Act PV 1
>Max PE per PV 1016
>VGDA 2
>PE Size (Mbytes) 32

This means:
* You can add up to 15 more disks/storage LUNs to this VG. (Max PV - Cur PV = 15)
Because you are now using only 1 disk, there is plenty of room for growth in this aspect.

* Each of those disks should be 32512 MeB or less in size; if you try to add a larger disk to this VG, only the first 32512 MeB is actually used. (PE size * Max PE per PV = 32512 MeB)
As a single physical disk can today hold one terabyte or more, this is very likely going to be a bottleneck.

* Therefore, the maximum total size of this VG is currently restricted to 520192 MeB. (PE size * Max PE per PV * Max PV = 520192 MeB)

* With vgmodify, you can increase the Max PE per PV value up to 65535; this would allow adding disks of 2097120 MeB (= slightly less than 2 TeB) to this VG, increasing the maximum size of the VG to 33553920 MeB = about 31 TeB.

* With vgmodify, you can also increase the Max PV value to 255; if you use vgmodify to change both values, the absolute maximum size is 509 TeB (which is way larger than currently supported by any filesystem).

When a LVM 1.0 VG is created, the system administrator must estimate how big the VG will grow in the future, and adjust the "PE size", "Max PE per PV" and "Max PV" values accordingly.

With vgmodify, you can change the "Max PE per PV" and "Max PV" values later; however, the PE size is set in stone at VG creation time and cannot be changed without destroying & recreating the VG.

It's usually easier to manage a few large disks than a large number of small disks. And if I can choose between a large PE size or a large "Max PE per PV", I would prefer larger PE size. Less PEs = smaller LVM metadata = smaller LVM configuration backup files in /etc/lvmconf on the root filesystem. (With large "Max PE per PV" and "Max PV", those files can become inconveniently large.)

The _minimum_ useful size of a LV is always one extent, so if you increase the PE size, the minimum size of a LV increases; but if you have a multi-terabyte VG, there is usually no need to micro-manage each megabyte individually.

MK
MK
newunix
Frequent Advisor

Re: PE and LE

i am liitle bit clear now

thanks for all responses