topic Re: cannot create volume group in Operating System - HP-UX

cannot create volume group

Paul Wright — Mon, 23 Jun 2003 13:25:12 GMT

On saturday we had a consultant in to hook up our HP9000 box to our new CX600.
She did a pvcreate and
mkdir /dev/vgtemp
mknod /dev/vgtemp/group c 64 0x030000
HOWEVER....................
when she tried to do a vgcreate, we got the following error message:
Increased the number of physical extents per physical volume to 42495.
vgcreate: Volume group "/dev/vgtemp" could not be created:
VGRA for the disk is too big for the specified parameters. Increase the
extent size or decrease max_PVs/max_LVs and try again.

I'm hoping someone out there has seen this before and can shed some light on it.
Thanks
Paul

Re: cannot create volume group

Massimo Bianchi — Mon, 23 Jun 2003 13:31:22 GMT

Hi,
vhen you create the vg, there are many option.

One of these is the PE size (-p option).
In a PV there can be a maximum of 65535.

But there are other rules.

One of this is that the number of PE * number of PV + a constat must fit, in bytes, in a single PE.

So, if you have a large disk and a large number of PV, you can overtake this limit.

To come around it, you can:

- use a bigger PE size
or
- limit the number of LV to something less than 255, i think 100 can suffice
or
- limit the number of PV, also here a maximum of 80 can help.

All these are option of the vgcreate:

SYNOPSIS
/usr/sbin/vgcreate [-f] [-A autobackup] [-x extensibility] [-e max_pe]
[-l max_lv] [-p max_pv] [-s pe_size] [-g pvg_name] vg_name
pv_path ...

Refer to the man page for all details .

HTH,
Massimo

Re: cannot create volume group

Uday_S_Ankolekar — Mon, 23 Jun 2003 13:31:35 GMT

It would be helpful if you could give us more details like how big is the disks. How many disks involved in this volume group etc..

do a pvdisplay on the disk to get disk information for configured numbers of physical extents and use diskinfo to get size of the disks
EX:
pvdisplay /dev/dsk/devicename
diskinfo /dev/rdsk/devicename

Goodluck..
-USA..

Re: cannot create volume group

A. Clay Stephenson — Mon, 23 Jun 2003 13:36:06 GMT

You need to add -e (max_pe) and -s (pe_size in MB) args to the vgcreate command.

Note that the maximum -e is 64K. You need to adjust the parameters so that max_pe X ps_size "fits" the largest LUN in this volume group. In general, a smaller pe_size is preferred.

Another possible source of error that will lead to very screwy error messages is duplicate minor device numbers in the group file. Make absolutely certain that there is not another 64/0x03000 device node.

Re: cannot create volume group

A. Clay Stephenson — Mon, 23 Jun 2003 13:36:13 GMT

Re: cannot create volume group

A. Clay Stephenson — Mon, 23 Jun 2003 13:36:33 GMT

Re: cannot create volume group

Anu Mathew — Mon, 23 Jun 2003 13:47:36 GMT

Hi Paul,

Please look at this thread where people responded to my similar problem.

Hey, your question is appearing twice to me.

Hope this helps,

~AM

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x10a50cb17a32d5118fef0090279cd0f9,00.html

Re: cannot create volume group

Paul Wright — Mon, 23 Jun 2003 13:59:57 GMT

Clay:
I tried your suggestions, adding -e and -s bit I still got the same message.

AM:
I'm tempted to just increase the PE size but I would rather leave them at 4MB if at all possible. Thanks for the info though.

Re: cannot create volume group

Mercadie — Mon, 23 Jun 2003 14:31:18 GMT

Hello,

If you want to avoid increasing the PE size you may create more lun on the cx600 with smaller size.

The disavantage is when running ioscan you will see a long list of disks (luns). If you have alternate links the number of seen disks will be very very very long.

ex: with 2 switches and a cx600 you will see 4 paths for each disk ...

Re: cannot create volume group

Massimo Bianchi — Mon, 23 Jun 2003 14:44:10 GMT

Hi,
try also with the "-p" and "-l".
After so many tests, i will re-issue a pvcreate, just to be sure it's all clean.

HTH,
Massimo