Reliability and availability assessment of storage area network extension solutions

Reliability is one of the key performance metrics in the design of storage area network extensions as it determines accessibility to remotely located data sites. SANs can be extended over distances spanning from hundreds to thousands of kilometers with optical or IP-based transport networks. The network equipment used depends on the storage protocol used for the extension solution. The present article provides analytical models developed for the calculation of long-term average downtimes, service failure rates, and service availability that can be achieved as a function of hardware/software failures, software upgrades, link failures, failure recovery times, and layer 3 protocol convergence times.