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Applicability of Object-Based Storage Devices in Parallel File Systems

Principal Investigator: Pete Wyckoff, OSC
Senior Personnel: Dennis Dalessandro, OSC
Senior Personnel: Ananth Devulapalli, OSC
Graduate Student: Nawab Ali, The Ohio State University

Funding Source: National Science Foundation, Grant No. 0621484
Duration: 9/1/2006 -- 8/31/2009

Description: While continued improvements in processing speeds and disk densities improve computing over time, the most fundamental advances come from changing the ways in which components interact. Delegating responsibility for some operations from the host processor to intelligent peripherals can improve application performance. Traditional storage technology is based on simple fixed-size accesses with little assistance from disk drives, but an emerging standard for object-based storage devices (OSDs) is being adopted. These devices will offer improvements in performance, scalability and management, and are expected to be available as commodity items soon.

When assembled as a parallel file system, for use in high-performance computing, object-based storage devices offer the potential to improve scalability and throughput by permitting clients to securely and directly access storage. However, while the feature set offered by OSD is richer than that of traditional block-based devices, it does not provide all the functionality needed by a parallel file system.

We will examine multiple aspects of the mismatch between the needs of a parallel file system, in particular PVFS2, and the capabilities of OSD. Topic areas include mapping data to objects, metadata, transport, caching and reliability. Trade-offs arise from the mapping of files to objects, and how to stripe files across multiple objects and disks, in order to obtain good performance. A distributed file system needs to track metadata that describes and connects data. OSDs offer automatic management of some critical metadata components that can be used by the file system. There are transport issues related to flow control and multicast operations that must be solved. Implementing client caching schemes and maintaining data consistency also requires proper application of OSD capabilities.

Our work will examine the feasibility of OSDs for use in parallel file systems, discovering techniques to accommodate this high performance usage model. We will also suggest extensions to the current OSD standard as needed.

Milestones:

  • Initial design and implementation of OSD initator and target
  • Extensions to enable usage over RDMA Networks also known as iSER

Publications:

Integrating Parallel File Systems with Object-Based Storage Devices
Ananth Devulapalli, Dennis Dalessandro, Pete Wyckoff, Nawab Ali and P. Sadayappan, Integrating Parallel File Systems with Object-Based Storage Devices Supercomputing 2007 (SC|07) Reno, NV, November 2007


iSER Storage Target for Object-based Storage Devices
Dennis Dalessandro, Ananth Devulapalli, and Pete Wyckoff, iSER Storage Target for Object-based Storage Devices, The 4th International Workshop on Storage Network Architecture and Parallel I/Os (SNAPI'07) , in conjunction with the 24th IEEE Conference on Mass Storage Systems and Technologies (MSST),San Diego, CA, September 2007
Attribute Storage Design for Object-based Storage Devices
Ananth Devulapalli, Dennis Dalessandro, Nawab Ali and Pete Wyckoff, Attribute Storage Design for Object-based Storage Devices, 24th IEEE-NASA Conference on Mass Storage Systems and Technologies (MSST 07), San Diego, CA, September 2007

Software Releases:

  • All we have released thus far is the iSER target code, other source will be posted soon. If immediate access is needed please email OSD Group mailing list otherwise watch this website for updates.
    Code availabe from: git://git.osc.edu/tgt.git or see Git on the Web