HP 3PAR RedHat and Oracle Linux Implementation Guide

3. Once the driver layer has discovered the device, run the echo statement for the RHEL OS
layer to discover the HP 3PAR devices. This command should also be used for a QLogic driver
installed as part of the OS install to initiate LUN discovery from both the driver and SCSI layer
together:
# echo " - <target number> <lun number>" > <device scan path>
If the device path is /sys/class/scsi_host/host2, the target is 0 (target 2:0:0), and
the exported device is LUN 1, then the echo statement would appear as the following example:
# echo "- 0 1" > /sys/class/scsi_host/host2/scan
The following message log provides an example of the resulting output:
kernel: Vendor: 3PARdata Model: VV Rev: 0000
kernel: Type: Direct-Access ANSI SCSI revision: 03
kernel: SCSI device sdv: 524288 512-byte hdwr sectors (268 MB)
kernel: SCSI device sdv: drive cache: write back
kernel: sdv: unknown partition table
kernel: Attached scsi disk sdv at scsi2, channel 0, id 0, lun 1
kernel: Attached scsi generic sg22 at scsi2, channel 0, id 0, lun 1, type 0
scsi.agent[12915]: disk at /devices/pci0000:00/0000:00:02.0/0000:01:00.2/
0000:03:0b.0/0000:04:04.0/host2/target2:0:0/2:0:0:1
• Alternatively, you can scan for all LUNs and targets for a given qla2xxx instance using
the following command:
# echo "- - -" > /sys/class/scsi_host/host2/scan
• If the device has changed its size, then issue the following command to obtain the new
disk size:
# echo 1 > /sys/class/scsi_device/2:0:0:1/device/rescan
Alternatively, you can use the rescan-scsi-bus.sh script, with the -r –nooptscan
options, to scan and discover LUNs.
Method 2 - Scan using add single device
This method involves performing a QLogic driver scan scsi-qlascan followed by adding LUNs
using the echo scsi add statement. To scan using add single device method, complete
the following steps.
NOTE: If you are using the QLogic driver that is installed during the OS installation, you can
skip performing the scsi -qlascan script and scan for devices using the following echo
command:
# echo " - <target number> <LUN number>" > <device scan path>
110 Allocating Storage for Access by the RHEL Host