vgcreate error

[Dennis Chao]

When I try to create a vg , I got the following message :
vgcreate:Cannot open the control file "/dev/vg14/group" No such device

But I have check a lot of time , I did have the device in /dev directory. I remove the /dev/vg14 and recreate it , still can not open.
We plan to create 18 vgs on our system , we had already create 13 vgs successfully but stop at 14th. We can not create 15,16,17,18 too ,what happen ?

[melvyn burnard]

could be a couple fo things.
What is your maxvgs set to in the kernel?
You can use SAM to check, select kernel configuration and then tuneable parameters, and se what maxvgs is set to.

Other thn that, ar eyo creating your group file in the directory correctly?

[A. Clay Stephenson]

Hi Dennis:

As Melvyn suggested this could be the maxvgs limit in the kernal. You may need to increase it and create a new kernel. The other problem you may be seeing is duplicate minor device numbers when you create your group files.
I suggest that you first do a strings /etc/lvmtab and see if that looks as you expect it. You can always do a vgexport /dev/vg14 and that will clean up the /dev/vg14 directory and the lvmtab. I would then do an ls -l on every /dev/vgxx directory and note the minor device number for each group file. Your new group file's minor device must must be unique. By convention, vg01's group file is typically Maj 64 Min 0x010000, vg02's is Ma 64 Min 0x020000, ... . That is just convention not a requirement, but the minor device numbers must be unique.

Hope this helps, Clay

[Santosh Nair_1]

More than likely you're running into a limit on the number of VGs that you're allowed to create on the system. Check the kernel parameter maxvgs using the command kmtune -q maxvgs. By default its set to 10, but I suspect that it's set to 13 on your system. Just increase it to 20-30 (to allow for future growth). You can do this by using the following command:

kmtune -s maxvgs=30
mk_kernel
kmupdate
shutdown -ry 0

-Santosh

[Sanjay_6]

Hi,

Have a look at this thread.

http://docs.hp.com/hpux/onlinedocs/os/KCparam.MaxVGs.html

If youe maxvgs parameter is correctly set in the kernel to accomodate the no of VG's you want to create and you are still getting the error, then check and see that /dev/vg_name/group file is properly getting created.

mkdir /dev/vg_name
mknod /dev/vg_name/group c 64 0x0n0000
n=1,2,3,.... and should be unique, check
ll /dev/*/group

Hope this helps.

thanks