The Vesta parallel file system

Abstract

The Vesta parallel file system is designed to provide parallel file access to application programs running on multicomputers with parallel I/O subsystems. Vesta uses a new abstraction of files: a file is not a sequence of bytes, but rather it can be partitioned into multiple disjoint sequences that are accessed in parallel. The partitioning-which can also be changed dynamically-reduces the need for synchronization and coordination during the access. Some control over the layout of data is also provided, so the layout can be matched with the anticipated access patterns. The system is fully implemented and forms the basis for the AIX Parallel I/O File System on the IBM SP2. The implementation does not compromise scalability or parallelism. In fact, all data accesses are done directly to the I/O node that contains the requested data, without any indirection or access to shared metadata. Disk mapping and caching functions are confined to each I/O node, so there is no need to keep data coherent across nodes. Performance measurements show good scalability with increased resources. Moreover, different access patterns are shown to achieve similar performance.

NDCouplingHDFS: A Coupling Architecture for a Power-Proportional Hadoop Distributed File System

“…Vesta [13], zFS [14] and Lustre [15], [16] all hashed the file pathname and/or some other unique identifier to determine the location of metadata. However, distributing metadata by hashing eliminates all hierarchical localities, and with them, many of the typical locality benefits of local file systems, for instance, the POSIX directory access semantics.…”

Evaluating I/O characteristics and methods for storing structured scientific data

“…While I/O has traditionally been a bottleneck in PCs, attempting to service the I/O requirements of an entire cluster has only augmented this problem to a much larger scale. Parallel file systems have helped to attain better I/O performance for clusters by striping data across multiple disks and are commonly used in most large-scale clusters [10,5,13,2,16].…”

Efficient metadata management in large distributed storage systems

“…For example, Vesta [4] and InterMezzo [2] use pathname hashing for both data allocation and location. If a hierarchical directory structure is used then the directories themselves may still be hot spots, even if the metadata for the files they contain is widely distributed.…”

“…The second metadata allocation technique, which we call pure hashing, uses hashing to widely distribute the namespace among the metadata servers [4]. Pure hashing assigns metadata to metadata servers based on a hash of the file identifier, file name, or other related values.…”