Management of disk space with REBATE

  • Authors:

  • Shahram Ghandeharizadeh;Douglas J. Ierardi

  • Affiliations:

  • Department of Computer Science, University of Southern California, Los Angeles, California;Department of Computer Science, University of Southern California, Los Angeles, California

  • Venue:
  • CIKM '94 Proceedings of the third international conference on Information and knowledge management
  • Year:
  • 1994

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Abstract

The past decade has witnessed a proliferation of respositories whose workload consists of queries that retrieve information. These repositories provide on-line access to vast amount of data and serve as an integral component of many application domains (e.g., library information systems, scientific applications, entertainment industry). Their storage subsystem is expected to be hierarchical consisting of memory, disk drives, and one or more tertiary storage devices. The database resides permanently on the tertiary storage devices and objects are swapped onto the magnetic disk drives on demand (and deleted once the disk storage capacity is exhausted). This may fragment the disk space over a period of time, resulting in a non-contiguous layout of an object across the surface of a disk drive. This is undesirable because, once the object is referenced, the disk drive is required to reposition its read head multiple times (incur seek operations) when retrieving the object, resulting in a low performance.This paper presents the design of REBATE. REBATE ensures the contiguous layout of each object across the surface of a disk drive by partitioning the available disk space into regions where each region manages objects of approximately the same size. We describe the tradeoffs of using REBATE and its possible limitations.