{"id":3070,"date":"2014-05-28T18:38:28","date_gmt":"2014-05-28T10:38:28","guid":{"rendered":"http:\/\/rmohan.com\/?p=3070"},"modified":"2014-05-28T18:39:29","modified_gmt":"2014-05-28T10:39:29","slug":"how-to-rescan-the-new-storage-lun-in-linux","status":"publish","type":"post","link":"https:\/\/mohan.sg\/?p=3070","title":{"rendered":"How to rescan the new Storage (LUN) in Linux without reboot"},"content":{"rendered":"
<\/div>\n
\n
In order to get the fiber channel adapters detail to rescan, list the \/sys\/class\/fc_host
\ndirectory. In old RHEL \u00a0host you will not be getting this listing. In this case you can use
\nthe \/sys\/class\/scsi_host directory but it will list all internal adapters too.1. In Order to scan New Lun we need to run LIP (Loop Initialization Protocol) on the
\ninterconnect to update the scsi layer to reflect the devices currently on the bus. LIP, is a
\nbus reset which cause the device addition and removal.<\/p>\n

# ls -l \/sys\/class\/fc_host
\ntotal 0
\ndrwxr-xr-x 3 root root 0 Feb 27 09:11 host0
\ndrwxr-xr-x 3 root root 0 Feb 27 09:11 host1<\/p>\n

2. Make the OS aware of the new storage
\n#echo “1” > \/sys\/class\/fc_host\/host1\/issue_lip
\n#echo “1” > \/sys\/class\/fc_host\/host2\/issue_lip
\n#echo “- – -” > \/sys\/class\/scsi_host\/host1\/scan
\n#echo “- – -” > \/sys\/class\/scsi_host\/host2\/scan<\/p>\n

 <\/p>\n

 <\/p>\n

Linux detecting SAN LUN without reboot<\/h3>\n

Detecting\u00a0SAN LUN without rebooting the server in Linux<\/p>\n

Rescan the bus by echoing the \/sys filesystem (only for Linux 2.6 kernels)<\/strong><\/p>\n

For Linux 2.6 kernels only, a\u00a0rescan\u00a0can be triggered through the \/sys interface without having to unload the host adapter driver or reboot the system. The following command will scan all channels, targets, and LUNs on host H.<\/p>\n

echo “- – -” > \/sys\/class\/scsi_host\/host_H\/scan<\/p>\n

Example:<\/p>\n

echo “- – -” > \/sys\/class\/scsi_host\/host1\/scan<\/p>\n

echo “- – -” > \/sys\/class\/scsi_host\/hos2\/scan
\necho “- – -” > \/sys\/class\/scsi_host\/hos4\/scan
\necho “- – -” > \/sys\/class\/scsi_host\/hos4\/scan<\/p>\n

OR
\nfor host in `ls \/sys\/class\/scsi_host\/`;do
\necho “- – -” >\/sys\/class\/scsi_host\/${host}\/scan
\ndone<\/p>\n

Note: Below is the explanation about wild card ..<\/p>\n

“- – -” in the above means C T L[“Channel on HBA” “Target SCSI id” “Lun”]
\n“- – -” is a wild card instead of specifying the C T L.<\/p>\n

3. After rescanning, confirm whether you are seeing the new storage disks LUN] by listing the
\ncontent under proc
\n# cat \/proc\/scsi\/scsi | grep scsi | uniq<\/p>\n

4. Now we can list the newly scanned LUN using ????fdisk -l???? command.
\n# fdisk -l<\/p>\n

5. If we have multipath configured then we can see as below:
\n# multipath
\n# multipath -ll<\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

In order to get the fiber channel adapters detail to rescan, list the \/sys\/class\/fc_host directory. In old RHEL host you will not be getting this listing. In this case you can use the \/sys\/class\/scsi_host directory but it will list all internal adapters too.1. In Order to scan New Lun we need to run LIP […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"_links":{"self":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/3070"}],"collection":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3070"}],"version-history":[{"count":2,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/3070\/revisions"}],"predecessor-version":[{"id":3072,"href":"https:\/\/mohan.sg\/index.php?rest_route=\/wp\/v2\/posts\/3070\/revisions\/3072"}],"wp:attachment":[{"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3070"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3070"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mohan.sg\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3070"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}