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-   -   how to re-scan SCSI BUS without restart (http://www.linuxquestions.org/questions/linux-newbie-8/how-to-re-scan-scsi-bus-without-restart-665990/)

prashanth_g83 08-28-2008 04:38 AM

how to re-scan SCSI BUS without restart
 
Hi all,

i newly joined to this community, with a new problem ,,

last week i installed SUSE-11. when i tried to hot swap the tape drive and re-scan the SCSI BUS by using the command rmmod aic7xxx and modprobe aic7xxx , its giving error message : MODULE AIC7XXX DOSNOT EXIST IN /PROC/MODULES.

if i restart the PC it works properly,

guys earlier i had gigabyte mother board with redhat , where in that i was able to do this.

can anybody help me to solve this plzz..

Fantasio 08-29-2008 05:25 AM

there is a script called "rescan-scsi-bus.sh", perhaps you have it on your system without to know it.

prashanth_g83 09-01-2008 11:20 PM

Hi Fantasio,

thanks a lot, its worked. i was not aware of this. its there in /bin. i tried from /bin, and its scanned.

thanks again

boy_named_suse 09-23-2011 01:03 PM

How are hardware changes automatically detected by the kernel?
 
Hi,

I realise that this thread has not been updated since 2008 so I'm not sure if anyone will see the question I have below, but if so, any helpful information would be very much appreciated please...

Apart from manually calling or running the rescan-scsi-bus.sh script mentioned in this thread, do most Linux distros automatically scan the PCI and SCSI buses at periodic intervals? I'm trying to get an understanding of exactly what happens when device disappears and reappears on the system.

I have my node attached by fiber to an EMC SAN (via a QLogic HBA with qla2xxx driver). If I pull the fiber cables out, I can see udev entries in /var/log/messages, telling me that the devices (sdb, sdc...) have been removed. Similarly, if I put the fiber cables back in, I can see udev entries in /var/log/messages, telling me that some devices have been added. The problem I'm actually having is that they are appearing with new (different) device names, so I'm trying to figure out how this detection is working at a relatively low level in the kernel.
Could you please help me to understand exactly what initiates the process that informs the kernel that the devices have been removed/added?
Is the PCI or SCSI subsystem periodically scanning for changes on the bus? My understanding (which may be quite incorrect) is that the PCI subsystem scans for devices on the bus. When it finds one it will register the new device with the device core and a kobject will be created in the kernel. Then the list of drivers for the PCI (or SCSI) subsystem will be queried until a matching driver for the new device is found. Then the driver will initialize the new device and the reference counter in the device's associated kobject will be incremented, at which time a uevent will be sent to udev.
Or, is it the driver that is responsible for detecting these changes and informing the device core in the kernel?

I'd eventually like to understand why different names are assigned to the devices when the cables are re-attached, but considering the topic of this thread, I'd very much like to know what informs the kernel of device status changes if the rescan-scsi-bus.sh script is not explicitly being run by me.

Thanks and regards,
boy_named_suse

polpak 09-24-2011 01:16 AM

Am NON-technical user of Suse Linux Enterprise 11 sp1


SLE11sp1 notices new hardware soon after plugged in.


Some time since advised to update software soon after plugged in external hardware, however it did and the update achieved.




UUID are new identifiers which do not change, they are persistent, based on metadata written on the device by certain applications.


UUID may also be used to access the device using the symlinks maintained by the operating system.


My sle11sp1 uses UUID to identify hardware, so as these do NOT change am not having problems with device names.




My sle11sp1 still uses

file: rescan-scsi-bus.sh


#!/bin/bash
# Skript to rescan SCSI bus, using the
# scsi add-single-device mechanism
# (c) 1998--2010 Kurt Garloff <kurt@garloff.de>, GNU GPL v2 or v3
# (c) 2006--2008 Hannes Reinecke, GNU GPL v2 or later
# $Id: rescan-scsi-bus.sh,v 1.52 2010/08/20 13:59:39 garloff Exp $

---deleted---


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