{"id":3140,"date":"2014-06-15T02:25:15","date_gmt":"2014-06-14T18:25:15","guid":{"rendered":"http:\/\/rmohan.com\/?p=3140"},"modified":"2014-06-15T02:25:15","modified_gmt":"2014-06-14T18:25:15","slug":"scan-for-new-scsi-device-to-detect-new-lun-without-reboot-centos","status":"publish","type":"post","link":"https:\/\/mohan.sg\/?p=3140","title":{"rendered":"Scan for New Scsi Device to Detect New Lun Without Reboot -Centos"},"content":{"rendered":"

This will scan the scsi host and no need to reboot to make devices(luns) visible.<\/p>\n

\n

echo \u201c- – -\u201d > \/sys\/class\/scsi_host\/host#\/scan<\/p>\n<\/blockquote>\n

Verify<\/p>\n

\n

fdisk -l
\ntail -f \/var\/log\/message<\/p>\n<\/blockquote>\n

Replace host# with actual value such as host0. You can find scsi_host value using the following command<\/p>\n

\n

# ls \/sys\/class\/scsi_host<\/p>\n<\/blockquote>\n

Now type the following to send a rescan request:<\/p>\n

\n

echo \u201c- – -\u201d > \/sys\/class\/scsi_host\/host0\/scan<\/p>\n<\/blockquote>\n

Can devices be rescanned in Linux OS without reloading the Linux driver?<\/strong><\/p>\n

A new LUN was added to the storage, but the LUN cannot be seen by the driver or the OS. Rebooting or reloading the driver would be too disruptive.<\/p>\n

Answer<\/strong><\/p>\n

There is a procedure which forces the driver to rescan the targets to allow a new device to be added. This triggers the driver to initiate a LUN discovery process.<\/p>\n

To force a rescan from the command line, type the following command<\/p>\n

# echo \u201cscsi-qlascan\u201d > \/proc\/scsi\/\/<\/p>\n

Where:<\/p>\n

– = qla2100, qla2200, qla2300 (2.4 kernel drivers) or qla2xxx (2.6 kernel drivers)
\n– = the instance number of the HBA<\/p>\n

After executing this command, force the SCSI mid layer to do its own scan and build the device table entry for the new device by typing the following command<\/p>\n

# echo \u201cscsi add-single-device 0 1 2 3? >\/proc\/scsi\/scsi<\/p>\n

Where:<\/p>\n

– \u201c0 1 2 3? = your \u201cHost Channel ID LUN\u201d<\/p>\n

The scanning must be done in the above mentioned order: first the driver (qla2300\/qla2200 driver, etc.), and then the Linux SCSI mid layer (i.e. OS scan).<\/p>\n

– See more at: http:\/\/linoxide.com\/how-tos\/linux-scan-scsi\/#sthash.CUZ4SYF6.dpuf<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

This will scan the scsi host and no need to reboot to make devices(luns) visible.<\/p>\n

echo \u201c- – -\u201d > \/sys\/class\/scsi_host\/host#\/scan<\/p>\n