Track-aligned Extents: Matching Access Patterns to Disk Drive Characteristics

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Track-aligned Extents: Matching Access Patterns to Disk Drive Characteristics (2002)

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by Jiri Schindler , John Linwood Griffin , Christopher R. Lumb , Gregory R. Ganger

Venue:	IN PROCEEDINGS OF THE 1ST USENIX SYMPOSIUM ON FILE AND STORAGE TECHNOLOGIES(FAST '02
Citations:	86 - 22 self

BibTeX

@INPROCEEDINGS{Schindler02track-alignedextents:,
    author = {Jiri Schindler and John Linwood Griffin and Christopher R. Lumb and Gregory R. Ganger},
    title = {Track-aligned Extents: Matching Access Patterns to Disk Drive Characteristics},
    booktitle = {IN PROCEEDINGS OF THE 1ST USENIX SYMPOSIUM ON FILE AND STORAGE TECHNOLOGIES(FAST '02},
    year = {2002},
    publisher = {}
}

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Abstract

Track-aligned extents (traxtents) utilize disk-specific knowledge to match access patterns to the strengths of modern disks. By allocating and accessing related data on disk track boundaries, a system can avoid most rotational latency and track crossing overheads. Avoiding these overheads can increase disk access efficiency by up to 50 % for mid-sized requests (100-500 KB). This paper describes traxtents, algorithms for detecting track boundaries, and some uses of traxtents in file systems and video servers. For large-file workloads, a version of FreeBSD's FFS implementation that exploits traxtents reduces application run times by up to 20 % compared to the original version. A video server using traxtent-based requests can support 56 % more concurrent streams at the same startup latency and buffer space. For LFS, 44 % lower overall write cost for track-sized segments can be achieved.

Keyphrases

track-aligned extent disk drive characteristic matching access pattern video server access pattern overall write cost ffs implementation mid-sized request concurrent stream traxtent-based request rotational latency disk-specific knowledge startup latency file system track boundary large-file workload track crossing overhead original version disk access efficiency buffer space track-sized segment modern disk disk track boundary

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