Initiating a connection to an iSCSI disk in Ubuntu

NOTE: This is Part 2 in a series on booting Ubuntu from an iSCSI disk. In the previous section, we setup an iSCSI target (a.k.a. server) which is sharing a blank iSCSI disk on the network. View all of the sections here.

Once again, the bulk of this post was unabashedly “borrowed” from howtoforge.com

The instructions in this post will work for any existing Ubuntu client, but if you are following along with the series, this is the part where you’ll want to boot your client machine from the Ubuntu CD / USB drive. Once booted, but before we start the installation, we’ll need to connect to the iSCSI disk so that it is available to install to. In order to do this, we’ll need to install the iSCSI initiator software onto the live (read: temporary) system.

When the installation wizard starts, drop to a shell. In my case, I right-clicked on the background and one of the context menu items was Terminal Emulator – perfect.

Jumping right in: get root, install the iSCSI initiator software and start the daemon

sudo su
root@client:~$ apt-get install open-iscsi
root@client:~$ /etc/init.d/open-iscsi start

Note: To reiterate, we are in a shell on the live system, so even though we just installed the iSCSI initiator software, when we reboot, everything we do here will be nullified. That’s not a bad thing; it’s just important to understand the distinction between the live (temporary) and installed (persistent) systems. We are setting up a connection from the live system so that the installation wizard can install the persistent system to the iSCSI disk.

Using the admin tool, run a discovery command to see what the server has to offer (where 192.168.0.101 is your server’s IP address)

root@client:~$ iscsiadm -m discovery -t st -p 192.168.0.101

You should see a description of the target disk that looks like this:

192.168.0.101:3260,1 iqn.2012-03.com.example:xbmc-server

If you don’t get a response, you may need to adjust your firewall settings on the server to allow access to port 3260 and/or confirm the iSCSI server is setup correctly.

Before we can connect we need to set the authentication settings which are stored in /etc/iscsi/nodes/iqn.2012-03.com.example:xbmc-server/192.168.0.101,3260,1/default. We can edit this file directly, or use the iscsiadm tool instead. These commands can be skipped if you opted not to use authentication when you setup your target.

root@client:~$ iscsiadm -m node --targetname "iqn.2012-03.com.example:xbmc-server" --portal "192.168.0.101:3260" --op=update --name node.session.auth.authmethod --value=CHAP
root@client:~$ iscsiadm -m node --targetname "iqn.2012-03.com.example:xbmc-server" --portal "192.168.0.101:3260" --op=update --name node.session.auth.username --value=<username>
root@client:~$ iscsiadm -m node --targetname "iqn.2012-03.com.example:xbmc-server" --portal "192.168.0.101:3260" --op=update --name node.session.auth.password --value=<password>

Finally, we can connect to the disk using the following command

root@client:~$ iscsiadm -m node --targetname "iqn.2012-03.com.example:xbmc-server" --portal "192.168.0.101:3260" --login

and for future reference, you can disconnect by using this command

root@client:~$ iscsiadm -m node --targetname "iqn.2012-03.com.example:xbmc-server" --portal "192.168.0.101:3260" --logout

You can use fdisk to confirm that the disk is available

root@client:~$ fdisk -l

Now that we have connected to the iSCSI disk, we are ready to continue with the installation, but I’ll leave that for another post.

Part 3: Install & Configure Ubuntu to boot from an iSCSI disk