Vgcretae failes with "A volume group is already using this major and minor number."

[tecnomatix]

Hi All,
I am using hpux 11.11 on rp7405.
I have already created 10 VG's.
I am trying to create additional Volume group but i dont know which minor number to use in the "mknod" command.

this is the group files:
crw-r----- 1 root sys 64 0x000000 Aug 12 16:31 /dev/vg00/group
crw-rw-rw- 1 root sys 64 0x011000 Sep 16 15:12 /dev/vgSI1/group
crw-rw-rw- 1 root sys 64 0x080000 Aug 26 18:35 /dev/vgimc1/group
crw-rw-rw- 1 root sys 64 0x090000 Sep 1 12:14 /dev/vglock/group
crw-rw-rw- 1 root sys 64 0x020000 Aug 28 13:27 /dev/vgtrp1/group
crw-rw-rw- 1 root sys 64 0x040000 Aug 26 18:35 /dev/vgtrp11/group
crw-rw-rw- 1 root sys 64 0x050000 Aug 26 18:35 /dev/vgtrp12/group
crw-rw-rw- 1 root sys 64 0x030000 Aug 26 18:06 /dev/vgtrp2/group
crw-rw-rw- 1 root sys 64 0x060000 Aug 26 18:06 /dev/vgtrp6/group
crw-rw-rw- 1 root sys 64 0x070000 Aug 26 18:06 /dev/vgtrp7/group


when I'm creating additional group file with
mknod group c 64 0x022000

and running vgcreate, i recieve the following error:
vgcreate: Volume group "/dev/vgSI2" could not be created:
A volume group is already using this major and minor number.
Please check the minor number of the "group" device file.

[T G Manikandan · Accepted solution]

What is your kernel parameter value

MAXVGS
By default it is 10.

You need to increase the value to create VGs more than 10.

[Jeff Schussele]

Hi,

I suspect your problem is not unique VG minor numbers, rather it's the value of the kernel parameter maxvgs - run

kmtune -q maxvgs

If it's the default value - 10 - you'll have to increase it to create any more VGs.
This will require a reboot.

Rgds,
Jeff

[Geoff Wild]

To see which ones are used, do a:

ll /dev/vg*/group

crw-r----- 1 root sys 64 0x000000 Oct 4 2002 /dev/vg00/group
crw-rw-rw- 1 root sys 64 0x010000 Oct 4 2002 /dev/vg01/group
crw-r--r-- 1 root sys 64 0x1e0000 Aug 22 13:45 /dev/vg30/group
crw-r--r-- 1 root sys 64 0x1f0000 Aug 22 14:01 /dev/vg31/group
crw-r--r-- 1 root sys 64 0x200000 Aug 22 14:13 /dev/vg32/group


Here, I'm using 00, 01, 1e, 1f, 20

your mknod is wrong - should be:

mknod group c 64 0x220000

That is if 22 is available...

Rgds...Geoff

[Jeff Schussele]

Oh & VG minor numbers are expressed in hexadecimal as follows

0x010000
0x020000
.
.
.
0x090000
0x0a0000
0x0b0000
0x0c0000
0x0d0000
0x0e0000
0x0f0000
0x100000
0x110000

The 0x022000 WILL confilict with a minor number for an LV in the vgtrp1 VG if there's 2 or more LVs in that VG.

Rgds,
Jeff

[T G Manikandan]

Also checked up a patch symptom for 11.11

LVM commands cumulative patch

http://www2.itrc.hp.com/service/patch/patchDetail.do?patchid=PHCO_24809&context=hpux:800:11:11

[Jeff Schussele]

I take the last one back...
It would conflict if the minor # was 0x020002
It would take 512 LVs in that VG to conflict with 0x02200.

Rgds,
Jeff

[Geoff Wild]

Just want to make it clear on the mknod command - to create a "group" file, you can not use the last 4 digits...they must remain 0000 as they are used for the lvols...well, the last 2 digits are...

0xXX0000

You can only use the digits XX

Remember, this is HEX - so if your kernel parameter MAXVGS is 80, then the highest minor number you can have is 4f (not 50).

As I said above, use:

mknod /dev/vgSI2/group c 64 0x220000

Rgds...Geoff