Disconnecting SCSI cables

[Joe White]

We have an ATL P3000 library connected to an N class running HPUX 11.0. The library has three SCSI cables each attached to its own SCSI controller card on the N class server. An ioscan -kf indicates that each card in turn is connected to its own external bus. If thre is no activity on the P3000 can we disconnect these cables from the system without shutting it down? Has anyone ever done this successfully? Thanks ahead for the response.

[Sanjay_6]

Hi Joe,

You can switchoff and remove the device without shuttting down the system by disconnecting the SCSI cable if the same is connected to a SCSI cable with inline terminator on the system side. Else you should power down the system and disconnect the device.

Thanks

[Patrick Wallek]

Joe,

I have disconnected the SCSI cable from one of my tape jukeboxes while the system was up and running with no system problems. I make sure I bring down the backup software that controls the jukebox beforehand so that there is less of a chance of somebody attempting to do something with the jukebox while the SCSI cable is unplugged.

All I can say is BE CAREFUL!!!!!!!

[A. Clay Stephenson]

Hi Joe,

I have both HP and StorageTek tape libraries and I have removed the cables without incident.
You will see some SCSI bus reset errors but I've never had a system crash doing this and the drives/robotics worked perfectly after restoring the connections. This does not mean that this is a good idea but sometimes you just can't shutdown. In all cases, I powerdown the library before removing cables.

Clay

[Darrell Allen]

Yes, as a general rule you can get away with a power down of the devices on a scsi chain and disconnect them. Should you do so? Should one play with fire? Not on my production servers or any others serving a useful purpose.

Darrell

[Deshpande Prashant]

Hi
I have shutdown & replaced the tape drives (DLT7000 ) connected on SCSI connection to N4000 machines, with out system crash.

Thanks
Prashant.

[Fabien DISSON]

Hi Joe,

When you connect or disconnect a hotplug device from a SCSI chain, you do almost the same from what you plan to do, no?

As far as I know, the problem comes from the capability of your device to support electrical
reset when you disconnect it from the SCSI bus.

Hotplug disks by example can support the risk, but what about your device?

When I disconnect a device like a DLT, I shut it down before to disconnect it. The risk is really small but not totaly avoided to burn the scsi circuits.

Also, The device you plan to disconnect must be alone on the SCSI bus (plus the card controller), or the other devices will have some problems...

Regards.