ISCSI

Introduction

This procedure will allow you to have a partition on a Linux server and then mount that partition on another Linux, Mac or Windows computer as an iSCSI device. On your host computer you need an allocated hard disk or a partition of a hard disk to be used as an iSCSI target.

All of the information below is available from the installation documentation.

/usr/share/doc/scsi-target-utils-0.0/README.iscsi

Installation

Lets get started by installing the iSCSI initiator on the Linux host.

yum install scsi-target-utils

Service Startup at Boot

chkconfig tgtd on
service tgtd start

Create a new target

tgtadm --lld iscsi --op new --mode target --tid 1 --targetname myvideofiles

NOTE: The target name must be in lowercase for windows to be able to successfully connect to it. If you have uppercase characters in the name you will get errors on connection.

Add a logical Unit

tgtadm --lld iscsi --op new --mode logicalunit --tid 1 --lun 1 -b /dev/hda4

NOTE: In this example I have created a partition that I will be using. That is why I have specified /dev/hda4. You may have specified /dev/hda or /dev/hdb for a whole hard disk, depending on your configuration.

Security

Allow All Initiators

tgtadm --lld iscsi --op bind --mode target --tid 1 -I ALL

This command will allow anyone to connect which is obviously insecure.

Based on IP Address

Individual IP

tgtadm --lld iscsi --op bind --mode target --tid 1 -I 10.10.0.24

Based on Subnet

tgtadm --lld iscsi --op bind --mode target --tid 1 -I 10.10.0.0/24

Authentication (CHAP)

First, create a user and password

tgtadm --lld iscsi --op new --mode account --user ''consumer'' --password ''Longsw0rd''

Next, add the users to an existing target device

tgtadm --lld iscsi --op bind --mode account --tid 1 --user ''consumer''

List Active Targets

tgtadm --lld iscsi --op show --mode target

Running the command on my server show the following output.

Target 1: myvideofiles
    System information:
        Driver: iscsi
        Status: running
    I_T nexus information:
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: deadbeaf1:0
            SCSI SN: beaf10
            Size: 0
            Backing store: No backing store
        LUN: 1
            Type: disk
            SCSI ID: deadbeaf1:1
            SCSI SN: beaf11
            Size: 65G
            Backing store: /dev/hda4
    Account information:
    ACL information:
        ALL

Stopping the tgtd Service

Currently there is no clean way to stop the tgtd service.

killall -9 tgtd

Possible Bug

When I reboot my Linux server it no longer displays or recognises any active targets. To get around this problem I add the commands to the servers start file as to configure active targets at boot.