how to change Instance number for a tape drive?

[Selvaraj]

Hi experts,

Good afternoon. We have Hp 9000 L2000 series nodes in our production site. Recently we swapped root hard disks from our lab nodes which has same hard configuration and same model. System boots up and started working very fine. So our production nodes changed to lab nodes and vice-versa. Only problem we noticed that our tapes drives instance number got changed from "0" to "1".

For eg,
/dev/rmt/0mn device files changed to /dev/rmt/1mn.

All our scripts referenced to "0mn" but not "1mn". We cannot reboot our production nodes now. Can u please suggest how to bring back original instance number without rebooting the box. If you feel reboot is neccessary, then what are the steps to be followed.

FYI, I already tried several options like insf -e, rmsf, insf -e -q, insf -e -q -I 0,
ioinit. Its again and again creating same "1mn" instead of "0mn". The ioinit command says error message as
"Instance number 0 already exists for class tape".

Kindly respond asap to earn your maximum points from me. Thnks in advance.

[Geno Church_1]

Attached is a step by step document....

Geno

[A. Clay Stephenson]

This is really simple. You can use ioscan to force a change of the bus instance number but that will can have the effect of redefining other things as well. Those names like 0m, 1mnb, ... don't mean anything to the computer; they are just for ous dumb ole humans. What the computer cares about are the major/minor device number tuples.

cd /dev/rmt
ls -l | lp (so that you have hard copy in front of you).

Let's say that 1m
Is now major numer 205 Minor Device 0x052000

All you need to do is,
rm 1m
mknod 0m c 205 0x052000

You now have a 0m with the correct major/minor device numbers. Repreat for the 1mn,1mnb, and 1b nodes.

This is the way device nodes were created in the dim mists of time before there were insf commands.

[Selvaraj]

Geno,
your step by step procedure is not working for me. But the procedure is right. The error message is:
"Instance number 0 already exists for class tape"
It exited without doing anything. So there is no point in rebooting the node also. Please suggest some other option to change instance number for this hardware.

Stephen,
your procedure will give us temporary solution. But the instance number remains same while performing ioscan. Basically we are using 1m/1mn device file for 0m/0mn which is not permanent solution. Can u please suggest us some other method to resolve this issue permanently. I tried to reboot a lab node to see whether it creates new device file with instance number "0". But the effort goes invain.

Any help from both of you would be highly appreciated.

[Selvaraj]

Can anyone help me out with this problem?

[Joshua Scott]

What ioscan options are you using to see the instance number?

Josh

[A. Clay Stephenson]

Actually, recreating the tape device nodes works perfectly and is preserved across boot as long as you don't issue a rmsf command.

[Selvaraj]

Josh,

I am using "ioscan -funC tape" as well as "ioscan -kf" to see instance number. Whenever I perform "ioinit -f /tmp/infile" with instance number as "0", I receive message as "Instance number 0 already exists for class tape".

Stephen,
you are right, the tape device file remains same until we issue "rmsf" command on that system. But that is not a permanent solution for us. Is there any toher method to perform ioinit by removing existing instance number and configure again with instance number "0".

[Joshua Scott]

I tried this out on a workstation I have here (rm'd all of the tape device files) then I did a mknod to recreate them. originally in /dev/rmt I had 0m, 0mn, etc. The ones I remade were 1m, 1mn, etc.

I then rebooted.

attached is the output of ioscan -kf

[Joshua Scott]

attached:
ioscan -funC tape