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
linux unix aix banner /etc/issue
Viewed 1762 times since Fri, Aug 3, 2018
UUIDs and Linux: Everything you ever need to know [Update]
Viewed 4757 times since Tue, Jul 17, 2018
Df command in Linux not updating actual diskspace, wrong data
Viewed 2618 times since Wed, May 30, 2018
Logowanie za pomocą kluczy Secure Shell
Viewed 2589 times since Thu, May 24, 2018
RHEL: Back-up/Replicate a partition table
Viewed 3077 times since Sun, May 27, 2018
LVM: Remove an existing Volume Group
Viewed 5072 times since Sat, Jun 2, 2018
Installing and Configuring an OCFS2 Clustered File System
Viewed 5549 times since Sat, Jun 2, 2018
Red Hat ADDING SWAP SPACE
Viewed 1825 times since Fri, Jun 8, 2018
RHEL: How to change a USER/GROUP UID/GID and all owned files
Viewed 20257 times since Sat, Jun 2, 2018
Use Fail2ban to Secure Your Server
Viewed 14132 times since Fri, Jul 5, 2019