How Scan LUN In Redhat Linux Vmware Guest OS

This Blog I am trying to give some examples that shows how to scan LUN from a Redhat Linux Vmware Guest OS (This example is from RHEL 3 ).Once LUNs are mapped for VM’s , it should be made visible to the OS.Below article explains and helps to scan and identify the disks/ LUNs that are mappped RHEL3.Below command will dispaly the available LUNS attached to the OS and its status.

# cat /proc/scsi/sg/devices
host chan id lun type opens qdepth busy online
0 0 0 0 0 5 28 0 1
0 0 1 0 0 1 28 0 1
0 0 2 0 0 1 28 0 1

# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: VMware Model: Virtual disk Rev: 1.0
Type: Direct-Access ANSI SCSI revision: 02
Host: scsi0 Channel: 00 Id: 01 Lun: 00
Vendor: VMware Model: Virtual disk Rev: 1.0
Type: Direct-Access ANSI SCSI revision: 02
Host: scsi0 Channel: 00 Id: 02 Lun: 00
Vendor: VMware Model: Virtual disk Rev: 1.0
Type: Direct-Access ANSI SCSI revision: 02

This will scan scsi for mapped LUNs

#echo “scsi add-single-device 0 0 3 0″>/proc/scsi/scsi

Now you can see new LUN added to the file or to the OS.

# cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: VMware Model: Virtual disk Rev: 1.0
Type: Direct-Access ANSI SCSI revision: 02
Host: scsi0 Channel: 00 Id: 01 Lun: 00
Vendor: VMware Model: Virtual disk Rev: 1.0
Type: Direct-Access ANSI SCSI revision: 02
Host: scsi0 Channel: 00 Id: 02 Lun: 00
Vendor: VMware Model: Virtual disk Rev: 1.0
Type: Direct-Access ANSI SCSI revision: 02
Host: scsi0 Channel: 00 Id: 03 Lun: 00
Vendor: VMware Model: Virtual disk Rev: 1.0
Type: Direct-Access ANSI SCSI revision: 02

Below fdisk command helps to find disk native url and disk details.
You can try this command before and after the lun scan.

# fdisk -l 2>/dev/null | egrep ‘^Disk’ | egrep -v ‘dm-’
Disk /dev/sda: 12.5 GB, 12582912000 bytes
Disk /dev/sdb: 37.7 GB, 37748736000 bytes
Disk /dev/sdc: 38.6 GB, 38654705664 bytes
Disk /dev/sdd: 53.6 GB, 53687091200 bytes
#

Tags: linux lun scan, linux scan, linux scan scsi, lun scan, lun scsi, proc scsi scsi

Category: Linux Administration