Joseph Herlant
version 1.0.0, 2014-07-19 : Initial version

Procedure tested on CentOS 6.5.

1. Configuring iSCSI target (server)

First, install the scsi-target-utils:

sudo yum install -y scsi-target-utils

Then configure your new target. For this, we took the following hypotheses (change them with whatever values you want):

  • Our domain is mydomain.com

  • The device we are using is /dev/vg_test/lv_test

  • Our client’s IP is 192.168.2.101 

sudo cat << __EOF__ >> /etc/tgt/targets.conf
# naming rule : iqn.<year>-<month>.<reversed.domain.name>:<any name>
<target iqn.2014-07.com.mydomain:target0>
  backing-store /dev/vg_test/lv_test
  # iSCSI client allowed to connect
  initiator 192.168.2.101
  # Auth info
  incominguser iscsiuser01 userpassword
</target>
__EOF__

Then get the service up and running and configure your firewall:

sudo chkconfig --levels 35 tgtd on
sudo service tgtd start
# Check that the new target is available
tgtadm --mode target --op show
# iptables configuration. Place your rule wherever you want!
sudo iptables -I INPUT 5 -p tcp -m tcp --dport 3260 -j ACCEPT
sudo service iptables save
sudo service iptables restart

2. Configuring iSCSI initiator (client)

First, install the iscsi-initiator-utils:

sudo yum install -y iscsi-initiator-utils

Configure your initiator iscsi identifier:

sudo cat << __EOF__ > /etc/iscsi/initiatorname.iscsi
InitiatorName=iqn.2014-07.com.mydomain:my_initiator01
InitiatorAlias=my_initiator01
__EOF__

And verify in your /etc/iscsi/iscsi.conf that the following fields are uncommented and with the right values:

node.startup = automatic
node.session.auth.authmethod = CHAP
node.session.auth.username = iscsiuser01
node.session.auth.password = userpassword

And restart your iscsid daemon:

sudo service iscsid restart
sudo chkconfig --levels 35 iscsid on

Now test that you can see the target’s device (our scsi target is 192.168.2.100). The following line should return something like "192.168.2.100:3260,1 iqn.2014-07.com.mydomain:target0".

sudo iscsiadm --mode discovery --type sendtargets --portal 192.168.2.100

Now make your target available as a new disk. This will make it persist accross reboot.

sudo iscsiadm --mode node --targetname iqn.2014-07.com.mydomain:target0 --portal 192.168.2.100

Check your available partition:

# Through fdisk, you should see your new disk
sudo fdisk -l
# Also check your iscsi sessions
sudo iscsiadm --mode session --op show
# use blkid to get your UUID
blkid
Important
Here you could notice that I used a LVM LV for the mount, so you can mount it directly. But usually we use a real LUN as target, so you’ll still have to create the partition using fdisk /dev/sdb (if your iscsi disk appeared as /dev/sdb) and format it using mkfs.ext4 /dev/sdb1.

To mount it automatically on boot, you’ll need to get the netfs daemon up and running and use the _netdev mount option in your /etc/fstab line. If you don’t do that, Linux will try to mount it BEFORE the network is setup.

sudo service netfs start
sudo chkconfig --levels 35 netfs on
mkdir /media/my/mountpoint
sudo echo -e "$(blkid /dev/sdb1 | cut -d" " -f2) \t /media/my/mountpoint \t ext4 \t _netdev,rw  \t 0 \t 0" >> /etc/fstab
sudo mount -a -O _netdev