Howtoforge posted a guide about using iSCSI on Ubuntu 10.04 (Initiator And Target)

This guide explains how you can set up an iSCSI target and an iSCSI initiator (client), both running Ubuntu 10.04. The iSCSI protocol is a storage area network (SAN) protocol which allows iSCSI initiators to use storage devices on the (remote) iSCSI target using normal ethernet cabling. To the iSCSI initiator, the remote storage looks like a normal, locally-attached hard drive.

  Using iSCSI On Ubuntu 10.04 (Initiator And Target)