Buffering and caching in large-scale video servers
Buffering and caching in large-scale video servers
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DOI：
10.1109/cmpcon.1995.512389
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发表时间：
1995-03
期刊：
影响因子：
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通讯作者：
A. Dan;D. Dias;R. Mukherjee;D. Sitaram;Renu Tewari
中科院分区：
文献类型：
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作者：
A. Dan;D. Dias;R. Mukherjee;D. Sitaram;Renu Tewari
视频点播服务器的特点是严格的实时限制，因为每个流都需要同步数据播放。系统的容量取决于每个流可接受的抖动（不满足实时约束的数据块的数量）。每个流的预读缓冲可避免因磁盘访问时间和排队延迟的变化而导致的播放中断。由于对存储的视频数据的访问模式严重倾斜，系统通常受到磁盘臂的限制。在这种情况下，从内存缓存提供视频流可以显着降低服务器成本。在本文中，我们研究了可用于大型视频服务器的各种缓冲和缓存策略的成本性能权衡。我们首先研究改变缓冲区大小、磁盘利用率和磁盘特性对系统整体容量的成本影响。随后，我们研究了利用时间局部性和工作负载波动的跨流内存缓存技术的成本效益。
Video-on-demand servers are characterized by stringent real-time constraints, as each stream requires isochronous data playout. The capacity of the system depends on the acceptable jitter per stream (the number of data blocks that do not meet their real-time constraints). Per-stream read-ahead buffering avoids the disruption in playback caused by variations in disk access time and queuing delays. With heavily skewed access patterns to the stored video data, the system is often disk arm-bound. In such cases, serving video streams from a memory cache can result in a substantial reduction in server cost. In this paper, we study the cost-performance trade-offs of various buffering and caching strategies that can be used in a large-scale video server. We first study the cost impact of varying the buffer size, disk utilization and the disk characteristics on the overall capacity of the system. Subsequently, we study the cost-effectiveness of a technique for memory caching across streams that exploits temporal locality and workload fluctuations.