, December 13, 2001
This talk will describe a method for matching access patterns to disk characteristics, called traxtents, the the benefits to video servers and file systems. By allocating and accessing data in track-sized extents that are aligned on track boundaries, traxtents can achieve 50% larger efficiency resulting in 1/3 shorter response times. In video servers, track-aligned access yields much smaller response time variance compared to traditional (track-unaligned) access methods, resulting in reduced buffer-space requirements and lower startup latencies for video streams. Even though traxtents utilize disk characteristics, a file system does not use any disk-specific information, but treats track boundary information merely as hints ensuring proper operation on all disks, as demonstrated by an implementation of traxtents in FreeBSD's Fast File System.
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