Implementation and Evaluation of the Block I/O Interface between the iSCSI Target and the Storage Device

The iSCSI protocol allows the block level storage data to be transported over the mature TCP/IP network. There are different interfaces between the iSCSI target and the storage device, such as disk I/O, file I/O and memory I/O interface. But these interfaces either lack of flexibility and universality or aggravate the system overhead and influence the system performance. Leveraging the flexibility and the performance is becoming critical to the iSCSI storage system. In this paper, we implement a block I/O interface between the iSCSI target and the storage device which shields the diversity of storage devices and offers higher performance than current iSCSI software implementations. Experiment results evaluated by iometer, a popular benchmark program, have shown dramatic performance gained with the block I/O interface.