Keynote Address II: Optimal Flash Partitioning for Storage Workloads in Google's Colossus File System

Janus is a system for partitioning the flash storage tier between workloads in a cloud-scale distributed file system with two tiers, flash storage and disk. The file system stores newly created files in the flash tier and moves them to the disk tier using either a First-In-First-Out (FIFO) policy or a Least-Recently-Used (LRU) policy, subject to per-workload allocations. Janus periodically computes the optimal partitioning of the available flash between workloads to maximize the total reads sent to the flash tier, based on the measured workload characteristics. This talk will describe the motivation behind the design of Janus, some of the analytical techniques used to model the workloads, the implementation, and some results.

Arif Merchant is a Research Scientist with the Storage Analytics group at Google, where he studies interactions between components of the storage stack. Prior to this, he was with HP Labs, where he worked on storage QoS, distributed storage systems, and stochastic models of storage. He holds the B.Tech. degree from IIT Bombay and the Ph.D. in Computer Science from Stanford University. He is an ACM Distinguished Scientist.