Tag Archives: usenix08

Measurement and Analysis of Large-Scale Network File System Workloads

usenix08_button.jpgAndrew W. Leung, Shankar Pasupathy, Garth Goodson, and Ethan L. Miller.

In this paper, we present the analysis of two large-scale network file system workloads.

In this paper we present the analysis of two large-scale network file system workloads. We measured CIFS traffic for two enterprise-class file servers deployed in the NetApp data center for a three month period. One file server was used by marketing, sales, and finance departments and the other by the engineering department. Together these systems represent over 22TB of storage used by over 1500 employees, making this the first ever large-scale study of the CIFS protocol.

We analyzed how our network file system workloads compared to those of previous file system trace studies and took an in-depth look at access, usage, and sharing patterns. We found that our workloads were quite different from those previously studied; for example, our analysis found increased read-write file access patterns, decreased read-write ratios, more random file access, and longer file lifetimes. In addition, we found a number of interesting properties regarding file sharing, file re-use, and the access patterns of file types and users, showing that modern file system workload has changed in the past 5–10 years. This change in workload characteristics has implications on the future design of network file systems, which we describe in the paper.

In Proceedings of the USENIX Annual Technical Conference 2008 (USENIX ’08)

Resources

  • A copy of the paper is attached to this posting.

largescale-usenix08.pdf

FlexVol: Flexible, Efficient File Volume Virtualization in WAFL

usenix08_button.jpgJ.K. Edwards, D. Ellard, C. Everhart, R. Fair, E. Hamilton, A. Kahn, A. Kanevsky, J. Lentini, A. Prakash, K.A. Smith, and E. Zayas.

We present the basic architecture of FlexVol volumes, including performance optimizations, and also describe the new features enabled by this architecture.

Virtualization is a well-known method of abstracting physical resources and of separating the manipulation and use of logical resources from their underlying implementation. We have used this technique to virtualize file volumes in the WAFL® file system, adding a level of indirection between client-visible volumes and the underlying physical storage. The resulting virtual file volumes, or FlexVol® volumes, are managed independent of lower storage layers. Multiple volumes can be dynamically created, deleted, resized, and reconfigured within the same physical storage container.

We also exploit this new virtualization layer to provide several powerful new capabilities. We have enhanced SnapMirror®, a tool for replicating volumes between storage systems, to remap storage allocation during transfer, thus optimizing disk layout for the destination storage system. FlexClone® volumes provide writable Snapshot® copies, using a FlexVol volume backed by a Snapshot copy of a different volume. FlexVol volumes also support thin provisioning; a FlexVol volume can have a logical size that exceeds the available physical storage. FlexClone volumes and thin provisioning are a powerful combination, as they allow the creation of light-weight copies of live data sets while consuming minimal storage resources.

We present the basic architecture of FlexVol volumes, including performance optimizations that decrease the overhead of our new virtualization layer. We also describe the new features enabled by this architecture. Our evaluation of FlexVol performance shows that it incurs only a minor performance degradation compared with traditional, nonvirtualized WAFL volumes. On the industry-standard SPEC SFS benchmark, FlexVol volumes exhibit less than 4% performance overhead, while providing all the benefits of virtualization.

In Proceedings of the USENIX Annual Technical Conference 2008 (USENIX ’08)

Resources

  • A copy of the paper is attached to this posting.

flexvol_usenix08.pdf