Red Hat Bugzilla – Bug 113731
"scsi add-single-device" and "scsi remove-single-device"
Last modified: 2013-08-05 21:03:56 EDT
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Description of problem:
Customers are in needs to have a reliable way to add/remove luns
into/from the system during run time for good reasons. The current
commands available to them (i.e. the 'echo "scsi add-single-device x x
x x" > /proc/scsi/scsi' and 'echo scsi remove-single-device x x x x" >
/proc/scsi/scsi') are known to be buggy and really not a production
For this particular issue from IT # 31269, the luns are on Dell/EMC
Clariion storage arrays. The server is attached to the array by a
QLA2340 HBA. The add-single-device and remove-single-device don't
work.With the application they're running, unloading the driver is not
an option. That will require shutting down the app or the database. If
they have to do that, they might as well reboot the system.
Note that with HP-UX the ioscan command can be used to rescan for new
devices and certain Sun devices can be dynamically added with the
Version-Release number of selected component (if applicable):
I know the scope of this work may not be trivial but please at least
make the commands work for a selected set of HBA, particularly qlogic
see http://download.qlogic.com/drivers/23292/readme.txt ---
9.6 How To Force Rescan Of Devices
Starting from driver version v6.06.00b12 there is support for the
which allows the user to force the driver to do re-scan of the devices to
allow a new device to be added. This triggers the driver to initiate lun
To do this from the command line:
# echo "scsi-qlascan" > /proc/scsi/<driver-name>/<adapter-id>
(qlogic driver re-scans)
Where <driver-name> can be either one : qla2100/qla2200/qla2300
<adapter-id> is the instance number of the HBA.
Once that has been done , user then can force the scsi mid layer to do its
own scan and build the device table entry for the new device:
# echo "scsi add-single-device 0 1 2 3" >/proc/scsi/scsi
(scsi mid layer re-scans)
Where "0 1 2 3" is replaced by your "Host Channel Id Lun".
The scanning has to be done in the above mentioned order. First the driver
(qla2300/qla2200 driver etc) and then the Linux scsi mid layer (i.e.
At this time any fix for this is beyond the scope of RHEL2.1 support status
(only critical security fixes are being accepted). Since there is a known
workaround, no other fix will be implemented.