MORRIS: A Distributed File System for Read-Intensive Applications

This paper presents the design and implementation of Modularly Optimized Round-robin ReadIntensive Storage (MORRIS), a file system which provides high throughput for read-intensive applications. NFSStripe, MORRIS’ primary component, is an NFS loopback server that achieves performance competitive with the traditional single-server model by distributing the task of data storage and retrieval over multiple machines. There are two main challenges associated with such a design. The first consists of structuring the underlying storage of the filesystem in such a way as to take advantage of multiple data servers, thereby allowing multiple concurrent read operations to be efficiently executed. We solve this problem by “striping” files across multiple StripeServer data servers in fixed-size blocks. Employing multiple machines to serve data from disk allows our system to fulfill multiple client requests at once, whereas a singleserver arrangement cannot. The second challenge is to ensure filesystem coherence as multiple concurrent client operations are issued to multiple independent servers. We solve this problem, while conferring minimal impact on the system’s performance, by designing a multiple-reader/single-writer locking protocol specifically suited to our system’s data structures.