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19 Dell EMC SC Series: Red Hat Enterprise Linux Best Practices | CML1031
Rescanning the HBAs while mapping and discovering new volumes does not have any negative impact on
the host.
#!/bin/bash
OSMajor=`uname -r |sed -rn 's/^.*(el.).*$/\1/p'`
echo "INFO: OS Major rev. ${OSMajor} detected!"
if [[ "$OSMajor" =~ !(el5|el6|el7|el8) ]];then
echo "WARN: OSMajor parameter of unknown value, exit 1"
exit 1
fi
for i in /sys/class/scsi_host/*
do
if [[ $OSMajor == "el5" ]];then
echo 1 >> ${i}/issue_lip
fi
echo "- - -" >> ${i}/scan
done
Note: Linux hosts cannot discover LUN ID 0 on demand. LUN ID 0 is typically reserved for the OS boot
volume in boot from SAN environment. The rescan-scsi-bus.sh provides the --forcerescan option and is a
possible method to discover LUN 0. All other volumes should be associated to LUN ID 1 or greater.
3.2.2 Identifying LUNs by WWNs
The most accurate way to identify a LUN on the host operating system is by its WWN, also known as WWID.
The SC Series array assigns a unique WWN for each LUN. The WWN contains the SC Series volume Device
Number or Serial ID which can be found in the DSM GUI under the general information section of the volumes
(see Figure 1). See section 5.4 on how to decode the WWN.