iShare: Balancing I/O Performance Isolation and Disk I/O Efficiency in Virtualized Environments

Performance isolation has long been a challenging problem for disk resource allocation in virtualized environments. While there have been many researches working on I/O performance isolation and disk utilization, none of them addresses the I/O performance isolation and disk utilization as a whole. To this end, we investigate the impact of current disk I/O performance isolation schemes on disk I/O utilization. Interestingly, our studies report that current isolation schemes bring unnecessary disk idle and reduce the overall disk I/O performance due to ignoring the disk states and characteristics of requests. Accordingly, we propose an adaptive proportional-share I/O scheduling framework, named iShare, in virtualized environments. iShare not only ensures I/O performance isolation through proportionally allocating time slices according to the weights of VMs, but also preserves high disk efficiency by detecting disk states and adaptively adjusting the time slice size based on characteristics of requests. We implement a prototype of iShare on the Xen platform. The experimental results show that iShare ensures I/O performance isolation while improving disk I/O efficiency: compared with Blkio (i.e, the default I/O performance isolation method in Xen), iShare increases disk I/O bandwidth by 58 % and slightly improves the I/O performance isolation for the sequential write applications. Copyright c ⃝ 2014 John Wiley & Sons, Ltd