google文件系統(tǒng)ppt課件(參考版)
2025-01-18 09:25本頁面
【正文】 very ast operations on file system metadata 9 Chunkserver ? Stores 64 MB file chunks on local disk using standard Linux filesystem, each with version number and checksum ? Read/write requests specify chunk handle and byte range ? Chunks replicated on configurable number of chunkservers (default: 3) ? No caching of file data (beyond standard Linux buffer cache) 10 Client ? Issues control (metadata) requests to master server ? Issues data requests directly to chunkservers ? Caches metadata ? Does no caching of data – No consistency difficulties among clients – Streaming reads (read once) and append writes (write once) don’t benefit much from caching at client 11 Client API ? Is GFS a filesystem in traditional sense? – Implemented in kernel, under vnode layer? – Mimics UNIX semantics? ? No。GFS: The Google File System Brad Karp UCL Computer Science CS Z03 / 4030 30th October, 2021 2 Motivating Application: Google ? Crawl the whole web ? Store it all on “one big disk” ? Process users’ searches on “one big CPU” ? More storage, CPU required than one PC can offer ? Custom parallel superputer: expensive (so much so not really available today) 3 Cluster of PCs as Superputer ? Lots of cheap PCs, each with disk and CPU – High aggregate storage capacity – Spread search processing across many CPUs ? How to share data among PCs? ? Ivy: shared virtual memory – Finegrained, relatively strong consistency at load/store level – Fault tolerance? ? NFS: share fs from one server, many clients – Goal: mimic
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