Evaluating the Effect of iSCSI Protocol Parameters on Performance

iSCSI is a new IETF standard protocol that makes it possible for a SCSI initiator (client) on one machine to exchange SCSI commands and data with a SCSI target (server) on another machine connected via a TCP/IP network. When an initiator establishes a connection to a target, a large number of standard parameters can be negotiated in order to customize many aspects of that connection. Both the initiator and target implementations can configure other parameters outside the iSCSI standard that also customize their interactions with the SCSI environment. This paper reports the major results from an extensive study of the effect of these parameters on iSCSI performance. It also develops a linear relationship between a number of them. We suggest settings that offer the best performance in the situations tested, with the belief that these settings offer the best available general guidance for configuring iSCSI until results from testing in more complex situations becomes available.