topic Re: Maximum number of phyisical extent per physical volume in Operating System - HP-UX

Maximum number of phyisical extent per physical volume

guna_1 — Mon, 10 May 2004 04:26:48 GMT

Hi,

I have some doubts about max no.of physical extents in a volume group .

1.what is the default Maximum number of phyisical extents per physical volume ?
2. How to change this value for already created volume group ?

( HPUX 11.00 )

Thanks in advance for the replys.

Rgds,
Guna

Re: Maximum number of phyisical extent per physical volume

Fabio Ettore — Mon, 10 May 2004 04:33:37 GMT

Hi,

I won't write a long procedure how to increase it, it was done by any ITRC people very well:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=237408

Anyway insert the string
max pe per pv
in the ITRC search above.

ITRC search is a very good tool for selfsolving.
I am sure that it will help you too.

Best regards,
Ettore

Re: Maximum number of phyisical extent per physical volume

G. Vrijhoeven — Mon, 10 May 2004 04:34:02 GMT

Hi Guna,

#vgdisplay
will display these settings. Ans Sorrie, but they are not changeable after volumegroup creation. A backup, create new one and restore is your only option.
You can specify them with a vgcreate ( -p max_pv] [-s pe_size] )

Regards,

Gideon

Re: Maximum number of phyisical extent per physical volume

Johan Lorimier — Mon, 10 May 2004 04:38:19 GMT

Hello,

you can see the mas PE per Pv of a volume group using vgdisplay command.
If not specified at the creation, the max PE is set to match the bigger disk you include in the vgcreate command.
But there is no way to change it after the VG creation.

Johan

Re: Maximum number of phyisical extent per physical volume

Geoff Wild — Mon, 10 May 2004 08:20:09 GMT

Default is 4 - can not change after creation.

PE is in 4MB chunks - so 4 PE - max disk size - 16GB, 8 PE, 32GB, etc...

You will have to recreate the VG if you are adding a larger disk to the vg....

Managing Disks:

http://docs.hp.com/cgi-bin/fsearch/framedisplay?top=/hpux/onlinedocs/5187-2216/5187-2216_top.html&con=/hpux/onlinedocs/5187-2216/00/00/84-con.html&toc=/hpux/onlinedocs/5187-2216/00/00/84-toc.html&searchterms=pe%7cmax&queryid=20040510-071853

Rgds..Geoff

Re: Maximum number of phyisical extent per physical volume

Patrick Wallek — Mon, 10 May 2004 08:31:45 GMT

The Default value of "Max PE perv PV" is 'size of disk in MV' divided by 'PE Size'. The default PE size is 4, however when you get into disks of about 18GB or larger you generally start needing to set the PE Size to something larger, so that then reduces Max PE per PV.

You should ALWAYS set the values for "PE Size", "Max PE per PV" manually when you create a VG. The reason is that you CAN NOT change ANY of the VG values once the VG has been created.

Re: Maximum number of phyisical extent per physical volume

guna_1 — Mon, 10 May 2004 09:31:06 GMT

Hi,

Thanks for all replys .

We can set the max PE per PV , while creation of VG , However how can we set this value for root volume group , while installing we creating the root vg , There i couldn't see the options to set the value for Max PE per Pv

For this I couldn't find the answer from search list.Please help me to resolve.

thanx and rgds,
Guna

Re: Maximum number of phyisical extent per physical volume

Patrick Wallek — Mon, 10 May 2004 09:36:07 GMT

When you install the OS from scratch, or from a make_tape_recovery tape, there is an area in the installer where all of this can be set.

If you choose the "advanced installation" from the menu, you will get a window with several tabs. You will want the "FILE SYSTEM" tab in there is an "Additional Tasks..." area. Select that and you get a list of 3 or 4 choices. To change the VG parameters you want either the "Volume Parameters" or the "Group Parameters" I can't recall exactly which one at the moment. You can change them there and they will then take effect when the installation is started.

Re: Maximum number of phyisical extent per physical volume

Sanjay_6 — Mon, 10 May 2004 09:53:49 GMT

Hi,

The default maximum number PE per PV is decided at the time of VG creation. Take a look at this thread. It may help.

http://www2.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000068583821

The itrc doc id is KBRC00000244.

Once a vg is created this value Max_PE per PV cannot be modified. You'll have to take a backup and recreate the VG with a new value.

Hope this helps.

Regds

Re: Maximum number of phyisical extent per physical volume

Jeff_Traigle — Mon, 10 May 2004 11:33:22 GMT

The default PE size is not strictly 4MB for root volume group creation. Looking at the config script for Ignite, the default gets set to 8MB for disks > 21GB, 16MB for disks >43GB, 32MB for disks > 83GB, and 64MB for disks > 175GB. IUX automatically increases max_physical_extents for disks > 9GB (per comment in config script). If you're installing the OS from CD/DVD, you should be able to manually set the PE size in the file system creation section, I would think... maybe under File System Options. (Haven't installed from CD/DVD in a while so not sure of the exact place, but that should be the general location to look for the option to change this.)

Re: Maximum number of phyisical extent per physical volume

Bill Hassell — Mon, 10 May 2004 13:39:19 GMT

SAM, Ignite/UX and vgcreate all have the ability to change the PE size as well as the extents. It is changed when the current size(s) are not adequate to define the selected disks. NOTE: all of these decisions must be done before vgcreate. vgcreate will automatically change the PE size and max PE count as long as *all* the disks are present on the command line. If there are more than few, then it is cumbersome (very long command line) so you must compute the total amount of storage (count disk mirrors as regular disks), then pick a PE size large enough to accomodate all the disks (and some growth, if expected). Create the VG and then add the disks. Once vgcreate is run, you CANNOT change the PE size or max number of PEs. Therefore, set these values to much larger than you'll ever need.