This paper explores interposed request routing in Slice, a new storage system architecture for high-speed networks incorporating networkattached block storage. Slice interposes a request switching lter | called a proxy | along each client's network path to the storage service e.g., in a network adapter or switch. The proxy intercepts request tra c and distributes it across a server ensemble. We propose request routing schemes for I O and le service tra c, and explore their e ect on service

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... ture. The Slice prototype uses a packet lter proxy to virtualize the standard Network File System NFS protocol, presenting to NFS clients a unied shared le volume with scalable bandwidth and capacity. Experimental results from the industrystandard SPECsfs97 workload demonstrate that the architecture enables construction of powerful network-attached storage services by aggregating cost-e ective components on a switched Gigabit Ethernet LAN.