Performance Evaluation of iSCSI Protocol for Mirroring Application.

Abstract

FC SAN has been the work-horse of the storage industry for quiet sometime now. It has prevailed and prospered in the enterprise-level storage environment due to its high performance and reliability. Data mirroring for disaster management and data recovery is gaining immense importance as the amount of data being stored increases exponentially. FC has been the default transport protocol for mirroring due to its performance advantages. But now with the demand for mirroring solutions for small & medium sized businesses being on the rise, the high acquisition and maintenance costs of FC have propelled iSCSI to be a cost-effective and viable alternative to FC. Traditionally iSCSI has been deemed unfit for delay sensitive applications due to its slow nature and lower throughput. In this thesis, we attempt to evaluate the performance of mirroring over iSCSI and show that it can be performed satisfactorily and economically, without requiring the costlier FC option. This study involves the use of a customized caching algorithm deployed on a SAN in order to exploit any performance enhancements when it comes to the response time for an application running on iSCSI. The cache tries to reduce the response-time for a write request for mirroring by deploying a two-level primary cache with a faster, smaller backup cache or a faster primary cache with a two-level backup cache. A comparative study of the results obtained for mirroring after deploying these caches over FC and iSCSI show that iSCSI provides adequate performance and reliability for a successful deployment of the mirroring application over it.