In this post we will discuss how to scan new LUNs allocated by storage team to a Redhat Linux system.
There are two ways of scanning the LUNs
Method 1:-
Find how many SCSI bus controllers you have
- Go to directory /sys/class/scsi_host/ and list it’s contents.
cd /sys/class/scsi_host/ [root@scsi_host]# ls host0 host1 host2 [root@scsi_host]#
- Here we can see we have three SCSI bus controllers. So in below command replace hostX with these directory names.
Run the Command ,
echo "- - -" > /sys/class/scsi_host/hostX/scan e.g. [root@cloudvedas]# echo "- - -" > /sys/class/scsi_host/host0/scan [root@cloudvedas]# echo "- - -" > /sys/class/scsi_host/host1/scan [root@cloudvedas]# echo "- - -" > /sys/class/scsi_host/host2/scan [root@cloudvedas]# echo "- - -" > /sys/class/scsi_host/host3/scan
TIP:- Here the “- – -” denotes CxTxDx i.e. Channel(controller) , Target ID and Disk or LUN number. This is asked in Linux Admin Interviews also.
- Repeat the above step for all three directories.
If you have FC HBA in the system you can follow the steps as below:-
- First check number of FC controllers in your system
#ls /sys/class/fc_host host0 host1 host2
- To scan FC LUNs execute commands as
echo "1" > /sys/class/fc_host/host0/issue_lip echo "1" > /sys/class/fc_host/host1/issue_lip echo "1" > /sys/class/fc_host/host2/issue_lip
- Verify if the new disk is visible now
fdisk -l |egrep '^Disk' |egrep -v 'dm-'
Method 2 :-
- Next method is to scan using SG3 utility. You can install it using
yum install sg3_utils
- Once installed run the command
/usr/bin/rescan-scsi-bus.sh
Wonderful website you have here but I was wanting to know if you knew of any message boards that cover the same topics talked about here?
I’d really like to be a part of online community where I can get comments
from other experienced people that share the same interest.
If you have any recommendations, please let me know. Cheers!
Hi,
Thanks for the suggestion. We are happy to inform you that our forum is now available. You can ask cloud related questions on it after registering.