Can not pvcreate disk

[simon peter]

Hi
I have a test box which was 11i using VxVm and now has been configured to 11.The problem I am experiencing is that when I try and pvcreate the spare disk I get the following message :

# pvcreate -f /dev/rdsk/c0t6d0
pvcreate: Could not perform LVM operation on VxVM disk "/dev/rdsk/c0t6d0".

I have tried to a # /usr/bin/dd if=/dev/zero of=/dev/dsk/c0t6d0 bs=64kbut get the following message :

/dev/zero: No such file or directory
dd: cannot open /dev/zero

Can anyone please advise.

Regards
Simon

[James R. Ferguson · Accepted solution]

Hi Simon:

'pvremove' is intended just for this situation:

# pvremove /dev/rdsk/cXtYdZ

Regards!

...JRF...

[Dietmar Konermann]

Hi, Simon!

If you are 100% sure that this disk is no longer active for VxVM you can use pvremove to get rid of the header. Pls note that pvremove is only available on >=11.11.

If /dev/zero is missing, you can create it using:

# mknod /dev/zero c 3 3

Best regards...
Dietmar.

[James R. Ferguson]

Hi (again) Simon:

BTW, to recreate '/dev/zero' (assuming someone removed it):

# mknod /dev/zero c 3 0x000004 #...on 11.x

# chown bin:bin /dev/zero
# chmod 666 /dev/zero

On 11.0 you can create '/dev/zero' too, but use:

# mknod /dev/zero c 3 0x000003 #...on 11.0

Regards!

...JRF...

[melvyn burnard]

or simply do
dd if=/stand/vmunix of=/dev/rdsk/c0t6d0 bs=1024k

[Dietmar Konermann]

James,

thanks for pointing out the minor number 4 for /dev/zero.

Just had a closer look... /dev/zero was introduced with 11.00 with minor 4. Yes, it's 4 for 11.00 also!

The minor 3 is some legacy thing that also returns "something"... usually zeros, so it was often abused as /dev/zero e.g. with 10.20.

Beginning with 11.00 one should really use the 4. I just tested with a 11.00 box that returned non-zero contents on minor 3! So take care.

Best regards...
Dietmar.

[James R. Ferguson]

Hi Dietmar:

Thank you, for the information. I can always count on you to really dig!

I meant to note that you can create a '/dev/zero' on *10.20* with a minor number of <3> but wrote "11.x" for some dumb reason.

I was vaguely aware that the 10.20 device was "usually zeros" and glad to know that it can't be relied upon for fidelity.

With warmest regards!

...JRF...

[simon peter]

Thanks guys for the help after following Dietmar Konermann i ran the dd again which took several hours all works ok.

[James R. Ferguson]

Hi (again) Simon:

Since you goal is to erase the VxVM information, 'pvremove' would be preferred since this is for what it is designed.

If you choose to use 'dd' with '/dev/zero', you would only need to do something like:

# dd if=/dev/zero of=/dev/rdsk/cXtYdZ bs=256k count=10

...should suffice nicely.

Regards!

...JRF...