11i vgcreate errors

[MTSU_SAN]

I've done the usual:
pvcreate /dev/rdsk/c3t0d1
mkdir /dev/vgcy1
mknod /dev/vgcy1/group c 64 0x0c0000
vgcreate -p 10 -l 32 -s 1 -g PV0 /dev/vgcy1 /dev/dsk/c3t0d1

and I get:
vgcreate: Cannot open the control file "/dev/vgcy1/group":
No such device

I can ll:
frank2:[/dev] # ll /dev/vgcy1
total 0
crw-r--r-- 1 root sys 64 0x0c0000 Oct 25 09:35 group

Why is this? Also, I've noticed Sam cannot see some of my disks, that ioscan can see (VA7400 disks), so I cannot do this through sam. Any suggestions?

[John Poff · Accepted solution]

Hi,

What is your 'maxvgs' kernel parameter set at? I think the default is 10. If you have 'maxvgs' set for 10, and you have less than 10 VGs defined, you'll have to pick a minor number between x01 and x0a. Otherwise, you'll have to bump up 'maxvgs'.

JP

[James R. Ferguson]

Hi:

If your kernel's 'maxvgs' parameter is the default (10), then you need to increase it to allow a 'vgcreate' for your device (0x0c = 12 decimal).

Regards!

...JRF...

[Ken Hubnik_2]

Can you use a character in the minor number

0x0c0000??

[Patrick Wallek]

Yes you can use characters in the minor #. It is a hex value, so 0c is 12, as James and John have mentioned.

Patrick

P.S. To Ken Hubnik - I have taken your old job at Wilsonart. E-mail me at wallekp@wilsonart.com with any advice or insights to the environment here.

[John Poff]

Ken,

Yes. The characters you use (0-9 and a-f) are to represent a hexadecimal number.

We typically set our 'maxvgs' parameter to 80. We have a box with lots of VGs, and I was running into an issue with creating a new VG one day. We didn't have as many VGs defined as our 'maxvgs' parameter, but I couldn't create any new VGs. It finally hit me that all our VG minor numbers were 00-09, 10-19, 20-29, etc., and we hadn't been using the higher hex numbers 0a-0f, 1a-1f, etc.

Maybe someday my three year old daughter will finally teach me how to count backwards and forwards in hexadecimal! :)

JP

[John Palmer]

With maxvgs defaulted to 10, the only valid values for group are 0x000000 through 0x090000 because the kernel reserves (maxvgs) structures and the minor number refers to a particular one.

I wouldn't be too concerned about sam, I'd recommend always using the LVM commands to create logical volumes. If you script the commands then it's easy to recreate things should the need arise (eg disaster recovery).

Regards,
John

[James R. Ferguson]

Hi (again):

For each increment in 'maxvgs' 4-8KB of lockable physical memory is consumed. Thus while you need to increase the parameter (and this requires a reboot) don't set it too artificially large while trying to anticipate your future requirements.

Regards!

...JRF...

[MTSU_SAN]

AAAh, yes, maxvgs. When we set up the new system, we just took the default, but I am setting up a Service Guard cluster,and so want the minor numbers the same on all nodes--silly me. Thanks!!