Improving iSCSI Memory Cache Hit through Prefetching to a Striped Disk

We propose a prefetching mechanism at the iSCSI initiator to improve the memory cache hit rate and attain better bandwidth utilization. By monitoring the scheduler run queue, the iSCSI initiator is able to move pages to the iSCSI initiator memory cache from the iSCSI target before a page fault occurs. To increase the effectiveness of prefetching, a small striped disk is used to keep more copies of the pages brought in from the iSCSI target. A prefetch analyzer analyzes both page fault and prefetch information which is later used by the iSCSI prefetcher to make better intelligent prefetching decisions. Our algorithm shows a 15% increase in sequential file reads and little or no performance improvement in random accesses.