Cloud storage systems typically use three-way random replication to guard against data loss within the cluster, and utilize cluster geo-replication to protect against correlated failures. This paper presents a much lower cost alternative to full cluster geo-replication. We demonstrate that in practical settings, using two replicas is sufficient for protecting against independent node failures, ...

Multi-tiered storage systems using tiers of SSD and traditional hard disk is one of the fastest growing trends in the storage industry. Although using multiple tiers provides a flexible trade-off in terms of IOPS performance and storage capacity, we believe that providing performance isolation and QoS guarantees among various clients, gets significantly more challenging in such environments. Ex...

This paper presents DITIS, a simulator for distributed and tiered file-based storage systems. In particular, DITIS can model system with up to three levels of tiers additional caches. Each tier cache be configured different number type media devices (e.g., HDD, SSD, NVRAM, DRAM), each their own performance characteristics. The utilizes the provided characteristics in fine-grained cost models (w...

OBJECTIVE The purpose of this study was to determine the number of thyroid nodule workups that could be eliminated and the number of malignant tumors that would be missed if the Society of Radiologists in Ultrasound (SRU) recommendations and the three-tiered system were applied to incidental thyroid nodules (ITN) detected at imaging. MATERIALS AND METHODS This retrospective study included ITN...