RHEL: Scan and configure new SAN (fibre channel) LUNs

# Tested on RHEL 5 & 6

# Identify host adapters on the system

systool -c fc_host

   Class = "fc_host"

     Class Device = "host3"
       Device = "host3"

     Class Device = "host4"
       Device = "host4"


ls /sys/class/fc_host
   host3  host4



# Rescan the hbas
# ------------------------------------------------------------------------------------------

echo "- - -" > /sys/class/scsi_host/host3/scan
echo "- - -" > /sys/class/scsi_host/host4/scan

# If this commands don't get to make new LUNs visible to system, you can try a "issue_lip"
# rescan.

# Take into account that rescanning via "issue_lip" will reset the HBAs what may cause
# a data loss if I/O operations are going on.
Use this type of scan only when necessary.
# In addition, as per Red Hat recommendations, the following restrictions must be observed
# when scanning storage interconnects:
#
# All I/O on the effected interconnects must be paused and flushed before executing the
# procedure, and the results of the scan checked before I/O is resumed.
#
# As with removing a device, interconnect scanning is not recommended when the system is
# under memory pressure. To determine the level of memory pressure, run the command
# "vmstat 1 100"; interconnect scanning is not recommended if free memory is less than 5%
# of the total memory in more than 10 samples per 100. It is also not recommended if
# swapping is active (non-zero 'si' and 'so' columns in the "vmstat" output). The command
# "free" can also display the total memory.

# I recommend to use "issue_lip" rescan only in case of servers that are discovering fibre
# SAN disk for first time:

# echo "1" > /sys/class/fc_host/host3/issue_lip
# echo "1" > /sys/class/fc_host/host4/issue_lip
0 (0)
Article Rating (No Votes)
Rate this article
Attachments
There are no attachments for this article.
Comments
There are no comments for this article. Be the first to post a comment.
Full Name
Email Address
Security Code Security Code
Related Articles RSS Feed
LVM: Reduce an existing Volume Group by removing one of its disks
Viewed 1275 times since Sat, Jun 2, 2018
Extending Linux LVM partitions - scripts
Viewed 5086 times since Sun, May 20, 2018
How to create a Systemd service in Linux
Viewed 1684 times since Mon, Dec 7, 2020
high swap space utilization in LINUX
Viewed 5702 times since Fri, Jul 13, 2018
RHEL: What is "SysRq key" and how to use it
Viewed 3867 times since Sat, Jun 2, 2018
stunnel Securing telnet connections with stunnel
Viewed 635 times since Sun, Dec 6, 2020
IPTABLES linux
Viewed 16133 times since Sat, Jun 2, 2018
Tropienie pożeracza dysku
Viewed 1466 times since Thu, May 24, 2018
SYS: Configure a local repository. local repo
Viewed 9459 times since Mon, Oct 29, 2018
Top 25 Best Linux Performance Monitoring and Debugging Tools
Viewed 4834 times since Sun, Sep 30, 2018