NFSv4 and High Performance File Systems: Positioning to Scale

The avant-garde of high performance computing is building petabyte storage systems. At CITI, we are investigating the use of NFSv4 as a standard for fast and secure access to this data, both across a WAN and within a (potentially massive) cluster. An NFSv4 server manages much state information, which hampers exporting objects via multiple servers and allows the NFSv4 server to become a bottleneck as load increases. This paper introduces Parallel NFSv4, extending the NFSv4 protocol with a new server-to-server protocol and a new file description and location mechanism for increased scalability.http://deepblue.lib.umich.edu/bitstream/2027.42/107881/1/citi-tr-04-2.pd

Replication Control in Distributed File Systems

We present a replication control protocol for distributed file systems that can guarantee strict consistency or sequential consistency while imposing no performance overhead for normal reads. The protocol uses a primary-copy scheme with server redirection when concurrent writes occur. It tolerates any number of component omission and performance failures, even when these lead to network partition. Failure detection and recovery are driven by client accesses. No heartbeat messages or expensive group communication services are required. We have implemented the protocol in NFSv4, the emerging Internet standard for distributed filing.http://deepblue.lib.umich.edu/bitstream/2027.42/107880/1/citi-tr-04-1.pd

Naming, Migration, and Replication for NFSv4

In this paper, we discuss a global name space for NFSv4 and mechanisms for transparent migration and replication. By convention, any file or directory name beginning with /nfs on an NFS client is part of this shared global name space. Our system supports file system migration and replication through DNS resolution, provides directory migration and replication using built-in NFSv4 mechanisms, and supports read/write replication with precise consistency guarantees, small performance penalty, and good scaling. We implement these features with small extensions to the published NFSv4 protocol, and demonstrate a practical way to enhance network transparency and administerability of NFSv4 in wide area networks.http://deepblue.lib.umich.edu/bitstream/2027.42/107939/1/citi-tr-06-1.pd

Reliable Replication at Low Cost

The emerging global scientific collaborations demand a scalable, efficient, reliable, and still convenient data access and management scheme. To fulfill these requirements, this paper describes a replicated file system that supports mutable (i.e., read/write) replication with strong consistency guarantees, small performance penalty, high failure resilience, and good scaling properties. The paper further evaluates the system using a real scientific application. The evaluation results show that the presented replication system can significantly improve the application's performance by reducing the first-time access latency to read the input data and by distributing the verification of data access to a nearby server. Furthermore, the penalty of file replication is negligible as long as applications use synchronous writes at a moderate rate.http://deepblue.lib.umich.edu/bitstream/2027.42/107950/1/citi-tr-06-2.pd

A replicated file system for Grid computing

To meet the rigorous demands of large-scale data sharing in global collaborations, we present a replication scheme for NFSv4 that supports mutable replication without sacrificing strong consistency guarantees. Experimental evaluation indicates a substantial performance advantage over a single-server system. With the introduction of a hierarchical replication control protocol, the overhead of replication is negligible even when applications mostly write and replication servers are widely distributed. Evaluation with the NAS Grid Benchmarks demonstrates that our system provides comparable and often better performance than GridFTP, the de facto standard for Grid data sharing. Copyright © 2008 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/60228/1/1286_ftp.pd

Hierarchical Replication Control

We present a hierarchical locking algorithm that dynamically elects a primary server in a replicated file system at various granularities. We introduce two lock types: shallow locks that control a single file or directory, and deep locks that lock everything in the subtree rooted at a directory. Experimental results show that for typical use cases, deep locks can make the overhead of replication control negligible, even when replication servers are widely distributed.http://deepblue.lib.umich.edu/bitstream/2027.42/107961/1/citi-tr-06-3.pd

Direct-pNFS: Scalable, transparent, and versatile access to parallel file systems

Grid computations require global access to massive data stores. To meet this need, the GridNFS project aims to provide scalable, high-performance, transparent, and secure wide-area data management as well as a scalable and agile name space. While parallel file systems give high I/O throughput, they are highly specialized, have limited operating system and hardware platform support, and often lack strong security mechanisms. Remote data access tools such as NFS and GridFTP overcome some of these limitations, but fail to provide universal, transparent, and scalable remote data access. As part of GridNFS, this paper introduces Direct-pNFS, which builds on the NFSv4.1 protocol to meet a key challenge in accessing remote parallel file systems: high-performance and scalable data access without sacrificing transparency, security, orportability. Experiments with Direct-pNFS demonstrate I/O throughput that equals or out performs the exported parallel file system across a range of workloads.http://deepblue.lib.umich.edu/bitstream/2027.42/107917/1/citi-tr-07-2.pd

Smartcard Integration with Kerberos V5

We describe our design and implementation of smartcard integration with Kerberos V5. Authentication is among the most important applications for smartcards and is one of the critical requirements for computer security. By augmenting Kerberos V5 with tamper-resistant hardware, we enhance the security of Kerberos V5 and offer a potential "killer application" leading to wider adoption of smartcard technology.http://deepblue.lib.umich.edu/bitstream/2027.42/107923/1/citi-tr-98-7.pd

PATHALIAS, or, The Care and Feeding of Relative Addresses

Pathalias computes electronic mail routes in environments that mix explicit and implicit routing, as well as syntax styles. We describe the history of pathalias, its algorithms and data structures, and our design decisions and compromises. Pathalias is guided by a simple philosophy: get the mail through, reliably and efficiently. We discuss the principles of routing in heterogeneous environments necessary to make this philosophy a reality

PATHALIAS or The Care and Feeding of Relative Addresses

Pathalias computes electronic mail routes in environments that mix explicit and implicit routing, as well as syntax styles. We describe the history of pathalias, its algorithms and data structures, and our design decisions and compromises. Pathalias is guided by a simple philosophy: get the mail through, reliably and efficiently. We discuss the principles of routing in heterogeneous environments necessary to make this philosophy a reality.http://deepblue.lib.umich.edu/bitstream/2027.42/107874/1/citi-tr-86-2.pd