topic Re: Available minor numbers/VG in Operating System - HP-UX

Available minor numbers/VG

Jamesbond313 — Tue, 19 Oct 2010 14:11:35 GMT

When creating a device file named group in the volume directory with the mknod command, what command do I use to obtain and display available minor numbers

Mknod /dev/vgname/group c major 0xminor

Thanks in advance for the assistance

Re: Available minor numbers/VG

vishnu.khandare — Tue, 19 Oct 2010 14:19:15 GMT

Hi James,

please use below command
#mknod /dev/vg0X/group c 64 0x0X0000
In Place of X change the no as per ur volume group for example vg01 as below

#mknod /dev/vg01/group c 64 0x010000

Hope this solves ur qery
Don't forget to assign points.

Regards
Vishnu Khandare

Re: Available minor numbers/VG

James R. Ferguson — Tue, 19 Oct 2010 14:20:01 GMT

Hi:

# ls -l /dev/vg*

If you are running a release less than 11.31 you will need to verify your kernel's 'maxvgs' value. Since vg00 counts as a used slot, a 'maxvgs' value of 10 means that you could have 'vg00..vg09' assuming you name your volume groups to match their minor number.

Regards!

...JRF...

Re: Available minor numbers/VG

Pete Randall — Tue, 19 Oct 2010 14:20:48 GMT

How about "ll /dev/vg*/group"? The output looks like this:

# ll /dev/vg*/group
crw-r----- 1 root sys 64 0x000000 Mar 15 2004 /dev/vg00/group
cr--r--r-- 1 root sys 64 0x010000 Mar 30 2004 /dev/vg01/group
crw-rw-r-- 1 informix informix 64 0x030000 Nov 26 2009 /dev/vg03/group

The minor numbers are the first two digits after "0x".

Pete

Re: Available minor numbers/VG

Pete Randall — Tue, 19 Oct 2010 14:20:57 GMT

Re: Available minor numbers/VG

Pete Randall — Tue, 19 Oct 2010 14:21:37 GMT

Apologies for the duplication. I forgot to check the retain spacing button.

Pete

Re: Available minor numbers/VG

Fraga — Tue, 19 Oct 2010 14:23:35 GMT

Hi,

It's simples:
/> ll /dev/*/group
crw-r----- 1 root sys 64 0x000000 Oct 30 2008 /dev/vg00/group

minor = 0x000000
major = 0x000000

Regards
EFS

Re: Available minor numbers/VG

Fraga — Tue, 19 Oct 2010 14:30:48 GMT

Correction:
major = 0x
minor = 64

Re: Available minor numbers/VG

Fraga — Tue, 19 Oct 2010 14:33:03 GMT

Sorry, my posts were confusing, this inverted ...............
I will go for here.

Re: Available minor numbers/VG

Tim Nelson — Tue, 19 Oct 2010 17:15:22 GMT

and to give you more information than ever needed for a simple "ls -ld /dev/vg*/group" command.

the maximum number of volume groups is equal to the kernel parameter MAXVGS in 11.11 and 11.23, i believe the limit is 255 in 11.31

cheers

Re: Available minor numbers/VG

Pete Randall — Tue, 19 Oct 2010 18:01:07 GMT

Fraga,

Still confusing. The major number is 64, which can be traced back to lsdev output to tell that this is an lvm device. The minor number is the first two digits following the 0x designation, in your example it would be 00, which most like indicates vg00.

Pete

Re: Available minor numbers/VG

VK2COT — Tue, 19 Oct 2010 19:52:38 GMT

Hello,

a) The LVM volume groups do not have to
have names starting with "vg", so
this is more appropriate:

# ll /dev/*/group

b) On HP-UX 11.31, if you use VG versions
2.x, you do not need all that nonsence
about mknod(1M). For example:

# vgcreate -V 2.2 ...

It automatically creates the volume group and picks up a free minor number. Absolutely
no need to run command mknod(1M) manually.

c) Finally, on HP-UX 11.31, VG versions 2.x
have major number 128. Only VG version 1.0
(traditionally being in use for the last
27-odd years), has major number 64.

In short, if you use latest HP-UX 11.31,
I would not even try to use VG version 1.0.

Cheers,

VK2COT

Re: Available minor numbers/VG

Bill Hassell — Tue, 19 Oct 2010 22:51:09 GMT

The only requirement is that each VG has a unique 2 digit hex number after the 0x. Although highly likely, 0x00 is probably vg00, but any hex value from 0x00 through 0xff will work as long as it is unique. To find what has already been used:

ll /dev/*/group | awk '{print $6,$NF}'

Now not all of these group files may be in use. The VG may be deactivated or it may have just been created with mkdir and mknod but never used in a VG.

Re: Available minor numbers/VG

Bill Costigan — Tue, 19 Oct 2010 22:52:15 GMT

One other thing.

The minor number is in hex.

So the number that would follow 0x090000 would be 0x0a0000. 0x100000 would follow 0x0f0000.

There doesn't have to be any relationship between the vg name and the minor number but each VG must have a unique minor number.

It is common for vg01 to have 0x010000 and vg02 to have 0x020000, etc. but it is not necessary.

Re: Available minor numbers/VG

Chandrahasa s — Wed, 20 Oct 2010 01:26:51 GMT

Hi,

ll /dev/vg*/group

If you have 11iv3 you no need to worry abour minor number you simply run vgcreate(no need to do mkdir vg and mknod)

chandra

Re: Available minor numbers/VG

Ismail Azad — Thu, 11 Nov 2010 21:34:04 GMT

Hi,

There is a convention that can be followed :-
/dev/vg05/lvol2
Minor number :- 0x050002
First 2 bits for volume group last 2 for logical volume (although very few people follow this as they give there own names for vgs and lvs). This is for LVM v1 . For v2 those 2 bits become 3 bits!. And hence in 11iv3 using LVM v2 we can have vgs and lvs upto fff which is more than 255 but only for LVM version2 and higher.

Regards

Re: Available minor numbers/VG

Torsten. — Thu, 11 Nov 2010 21:35:46 GMT

And again - without telling your OS version you cannot get an exact answer ...

Re: Available minor numbers/VG

SoorajCleris — Fri, 12 Nov 2010 20:34:30 GMT

Hi,

addon,

If your maxvgs ( prior to 11iV3) parameter is 8 and you have used minor number -07- to create a group file ( 0x070000) , you will not be able to create anymore VG , even there is only two VGs existing in the system.

Vgcreate command will give you an error which you have never seen ..

enjoy it !!!

Regards,
Sooraj

Re: Available minor numbers/VG

SoorajCleris — Fri, 12 Nov 2010 20:36:41 GMT

If you liked it , assign the points!!!!