Performance Evaluation Of Different Scheduling Algorithms With ISCSI Traffic

iSCSI (internet SCSI, Internet Small Computer System Interface) is a popular SAN (storage area network) protocol, which provides high-speed storage access and high reliability. iSCSI adopts TCP/IP as its lower level protocol instead of the traditional Fibre Channel. Therefore, ower levels are not specified in iSCSI standard.This article is centered on performance evaluation of scheduling algorithms with iSCSI traffic. As a SAN protocol, iSCSI should ensure the network transmission performance as a critical factor, while scheduling algorithms of the nodes in the network links has a certain effect on the performance of data flows. Most present researches focus on higher levels and related applications, but the effect of algorithms is left nearly unnoticed.The main work of this paper can be summarized as follows:1. iSCSI model is built up with network simulator ns-2 and verified. The model is coded in OTcl scripts with application of the ns-2 split object feature, which fits for customed ns-2 installations that is extended and re-compiled. The model is implemented in different network topologies, and simulations are carried out with the topologies. The data produced is then compared with that of other model and real iSCSI devices to prove that the model generates traffic with iSCSI feature.2. ns-2 scenarios are built for iSCSI simulations, for each scheduling algorithms, network topologies are configured, and statistic data are collected. The scenarios are designed close to iSCSI implementations, the algorithms evaluated are FIFO, FQ, WFQ, DRR and SRR. To ensure that the statstic data accord to real iSCSI traffic, random variables are set up for start times of iSCSI sessions. With repetitive simulations, and stastical method taken, the final data is derived from the records.3. The data is analized to evaluate the performance of the algorithms. Performance parameters such as delay, delay jitter, average rate and rate jitter are compared, furthermore, effects of the parameters and other performance related factors are discussed. The conclusion is that DRR offers advanced performance, fits iSCSI traffic most among the several scheduling algorithms.