Messages in this thread |  | | From | Russell King <> | Subject | Re: The advantage of modules? | Date | Mon, 8 Jan 2001 21:50:55 +0000 (GMT) |
| |
Michael Meissner writes: > Quoting from drivers/scsi/scsi.c: > > /* > * Usage: echo "scsi add-single-device 0 1 2 3" >/proc/scsi/scsi > * with "0 1 2 3" replaced by your "Host Channel Id Lun". > * Consider this feature BETA. > * CAUTION: This is not for hotplugging your peripherals. As > * SCSI was not designed for this you could damage your > * hardware ! > * However perhaps it is legal to switch on an > * already connected device. It is perhaps not > * guaranteed this device doesn't corrupt an ongoing data transfer. > */ > > so my take is unless you explicitly use hotplug devices (I wasn't), that > it is much safer to unload the driver, unattach/attach scsi devices, and > then reload the driver (which will scan the scsi bus for devices), which > you need modules for.
I don't believe that is what it's trying to say. There have been instances in the past where unplugging a SCSI device from a powered on SCSI bus can result in blown terminator power fuses and the like. Whether this still applies today, I don't know (are active terminators better or worse than passive when it comes to this type of thing?) However, what I do know is the following, and I learnt it the hard way:
I once had a machine and other stuff on a 4-way mains connector block that has been used for many years. Unknown to me, the earth wire had become intermittent. I was just about to connect another peripheral which was directly connected to the wall socket to this computer, and I happened to touch the connector body on both the peripheral and the computer. I now know what a shock of >120V feels like.
Now, imagine what would happen if you connect a SCSI device, where this condition exists, and the first thing that makes contact is the SCSI databus. Say goodbye to most, if not all devices on that SCSI bus. _____ |_____| ------------------------------------------------- ---+---+- | | Russell King rmk@arm.linux.org.uk --- --- | | | | http://www.arm.linux.org.uk/personal/aboutme.html / / | | +-+-+ --- -+- / | THE developer of ARM Linux |+| /|\ / | | | --- | +-+-+ ------------------------------------------------- /\\\ | - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
|  |