Howto hot-remove SCSI device safely in HP-UX

[OPM Marienborg]

We are currently using a portable tape-drive to do ignite-tapes etc. My question follows, is it possible to remove the tape drive while the system is powered on? We tried doing that the other day and the system crashed. Is there a command to tell the system to release/unbind a HW-path?

thanks,

[Andrew Rutter · Accepted solution]

hi,

There is no command to release the hardware path as far I know, and you should be able to remove the external tape drive quite easily without problem.

The only reason the system may have crashed is if the system was using or thought it was using the device, ie something still had a hold on a process associated with the device.

Of course if you need to remove the device it must be last on the bus, not in the middle of a daisy chain, preferably on its own aswell. This could cause it to crash if the bus hung due to terminating other devies aswell unexpectedly.

one thing you could do is check the processes running if it is on its own bus, prior to removal.

Also check status of drive with

#mt -t stat
and if necessary make sure it is offline

#mt -t offline

of course removing the drive physically will still leave any device files present, and you will have an no_hw in ioscan output.


Andy

[paolo barila]

Yes, just check that is not working.

If you want you can remove the special files:

# ioscan -fnC tape

sample output:

Class I H/W Path Driver S/W State H/W Type Description
=====================================================================
tape 0 0/0/1/0.4.0 stape CLAIMED DEVICE HP C1537A


# rmsf -H 0/0/1/0.4.0

I would anyway do "rmsf" only to change the tape.

Paolo

[Steven E. Protter]

Shalom,

Removing scsi devices sometimes produces an lbolt in /var/adm/syslog/syslog.log

If its caused by removing a device its okay. If it is caused by another device it means disk failure and should be followed up on.

Your crash may be caused by a missing patch.

vi /var/rc.config.d/savecrash

Make sure the variable in the file is set to 1.

Then if there is a subsequent crash you will get a crash dump in /var/adm/crash

You will be able post crash to run q4 analysis and your friendly, local HP response center will be able to provide you a list of patches to install.

SEP

[OPM Marienborg]

Thanks, I'll try this next time.

[Devender Khatana]

Hi,

One reason for crash could be that the device was switched on while removed?

There is no need to remove device file for the device before physically removing it.

Ensure the device to be powered down when attaching/detaching not the server.

HTH,
Devender

[Carl Munnelly]

What type of card is the tape drive connected to is it a self terminating SCSI card.

Crash could be caused if not self terminating as SCSI termination would be broken and system would panic.