ISCSI is proposed as a possible solution to building future storage systems. However, using iSCSI raises numerous questions about its implications on system performance. This lack of understanding of system I/O behavior in modern and future systems inhibits providing solutions at the architectural and system levels. The authors’ main goals in this work are to understand the behavior of the application server (iSCSI initiator), to evaluate the overhead introduced by iSCSI compared to systems with directly attached storage, and to provide insight about how future storage systems may be improved. They examine these questions in the context of commodity iSCSI systems that can benefit most from using iSCSI. They use commodity PCs with several disks as storage nodes and a Gigabit Ethernet network as the storage network.