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18 Dell EMC SC Series: Red Hat Enterprise Linux Best Practices | CML1031
3. To identify the correct Linux system HBAs, obtain the HBA information on the Linux system (see
sections above), and cross-reference them with the list displayed.
3.2 Discovering and identifying SC Series volumes on a Linux system
Once the server object for the Linux system is created, present/map the SC Series volumes to the Linux
system. This section provides information on how to discover and identify these mapped volumes on a Linux
system.
The driver modules for the QLogic 24xx/25xx Series HBAs and the Emulex HBAs come with the base kernel
code on RHEL 6 and newer systems. The following instructions apply to the default HBA driver modules. If
the vendor (QLogic, Emulex) proprietary driver has been used, consult the vendor specific documentation for
instructions and details.
3.2.1 Scanning for LUNs
The easiest way to scan for new volumes is to use the rescan-scsi-bus.sh command provided by the
sg3_utils package. The command scans all SCSI buses (FC/iSCSI or SAS), then discovers and creates
device files including the multipath devices if multipath is enabled.
Scan and discover new LUNS on all SCSI buses:
# /usr/bin/rescan-scsi-bus.sh –a
If sg3_utils package is not available to the system, the following sample script can be adopted to scan for
new volumes. The sample script performs the following tasks. This script can be used to discover both FC
and iSCSI devices presented to the host.
• Identifies the major revision number of the Linux operating system
• Applies the echo command to the respective hostX devices within the /sys/class/scsi_host/ folder
• Scans the HBA ports, and discovers and identifies existing and new volumes presented to the host
from the storage system
Note: STDOUT is not generated from this script. Check the contents of /var/log/messages or the output from
the dmesg or lsscsi commands to identify any newly discovered volumes.