how to create volumegroup

[Franky Leeuwerck_2]

Hello,

I have a SAN ( eva3K ) with disks presenting to my unix box.

When I try to create a new volumegroup in SAM, I get this error :
No device files for the selected device were found in /dev.

Can someone tell me what is wrong ?

Thanks in advance
Franky

[Uwe Zessin]

SAM cannot deal with the EVA's devices - you need to use the command line.

[Luk Vandenbussche]

Try it manually

mkdir /dev/vgXX
mknod /dev/vg00/group c 64 0x0X0000
pvcreate -f /dev/rdsk/cxtydz
vgcreate vgXX /dev/dsk/cxtydz

[Franky Leeuwerck_2]

Hi Luk,

I'm not sure about the variables in the command line solution.

Ioscan shows me the presented disk like this :
disk 4 255/255/0/0.1 sdisk CLAIMED DEVICE HSV100 HP
/dev/dsk/c15t0d1 /dev/rdsk/c15t0d1

The volume that I want to create should be /dev/vg01 .

What should I use for variables in your statements ?

Franky

[Luk Vandenbussche]

Franky,

Here is the exact command

mkdir /dev/vg01
mknod /dev/vg01/group c64 0x010000
pvcreate -f /dev/rdsk/c15t0d1
vgcreate vg01 /dev/dsk/c15t0d1

You should be able to create logical volumes through sam now

[Franky Leeuwerck_2]

Luk,

Thanks for your further inputs.

Can you tell me why the ' 0x010000 ' ?
I need to create about 7 volumegroups.
Should I use ' 0x010000 ' for each of these.

Franky

[Scott McIntosh_2]

No, the minor number in the group file for each volume group must be different.

So if I did "ll /dev/vg*/group", I should see different numbers in the first two digits of the minor number:

crw-r----- 1 root sys 64 0x000000 Oct 28 2002 /dev/vg00/group
crw-rw-rw- 1 root sys 64 0x010000 Nov 26 2002 /dev/vg01/group

[Franky Leeuwerck_2]

Thanks Scott.

Can these numbers be chosen randomly, or is there a specific order ?

Franky

[Luk Vandenbussche · Accepted solution]

Francky,

It is hexadecimal.
It is defined by the kernel parameter maxvgs and it must be unique for each volumegroup.

The default kernel parameter is 10

[Scott McIntosh_2]

Order is not important, they just have to be unique for each volume group present on the system. This becomes a more significant question for cluster environments, for example.

So you could have 0x00..., 0x01..., and 0x06..., for example.

Thanks,
Scott
HP Support

[Franky Leeuwerck_2]

Thanks for your input, Luk and Scott.
This solves my problem.

Franky :

Once a vg is created, can one easily change the physical extend size ( from 4 to 16 MB f.i. ) ?

[Franky Leeuwerck_2]

Another question .
If I have multiple disks presented for a volumegroup, should I simply run the following statements for every disk to add :
pvcreate -f /dev/rdsk/cxxt0dy
vgcreate vg01 /dev/dsk/cxxt0dy

[Luk Vandenbussche]

Franky you have to define it when you create it

vgcreate -s 16 /dev/vg01 /dev/dsk/c15t0d1

So repeat my steps above with this option.

Don't forget the following first

vgchange -a n vg01
vgremove vg01

[Luk Vandenbussche]

To add more disks

vgextend vg01 /dev/dsk/cxtydz