Date Added: May 2012
A common problem with disk-based cloud storage services is that performance can vary greatly and become highly unpredictable in a multi-tenant environment. A fundamental reason is the interference between workloads co-located on the same physical disk. The authors observe that different IO patterns interfere with each other significantly, which makes the performance of different types of workloads unpredictable when they are executed concurrently. Unpredictability implies that users may not get a fair share of the system resources from the cloud services they are using. At the same time, replication is commonly used in cloud storage for high reliability.