cloudcomputing-文庫吧資料
2025-07-21 18:09本頁面
【正文】 ummary ? Cloud puting is a kind of work service and is a trend for future puting ? Scalability matters in cloud puting technology ? Users focus on application development ? Services are not known geographically Counting the numbers vs. Programming model ? Personal Computer ? One to One ? Client/Server ? One to Many ? Cloud Computing ? Many to Many What Powers Cloud Computing in Google? ? Commodity Hardware ?Performance: single machine not interesting ?Reliability ? Most reliable hardware will still fail: faulttolerant software needed ? Faulttolerant software enables use of modity ponents ?Standardization: use standardized machines to run all kinds of applications What Powers Cloud Computing in Google? ? Infrastructure Software ?Distributed storage: ? Distributed File System (GFS) ?Distributed semistructured data system ? BigTable ?Distributed data processing system ? MapReduce What is the mon issues of all these software? Google File System ? Files broken into chunks (typically 4 MB) ? Chunks replicated across three machines for safety (tunable) ? Data transfers happen directly between clients and chunkservers GFS Usage Google ? 200+ clusters ? Filesystem clusters of up to 5000+ machines ? Pools of 10000+ clients ? 5+ Petabyte Filesystems ? All in the presence of frequent HW failure BigTable ? Data model ?(row, column, timestamp) ? cell contents BigTable ? Distributed multilevel sparse map ? Faulttolerance, persistent ? Scalable ? Thousand of servers ? Terabytes of inmemory data ? Petabytes of diskbased data ? Selfmanaging ? Servers can be added/removed dynamically ? Servers adjust to load imbalance Why not just use mercial DB? ? Scale is too large or cost is too high for most mercial databases ? Lowlevel storage optimizations help performance significantly ? Much harder to do when running on top of a database layer ? Also fun and challenging to build largescale systems BigTable Summary ? Data model applicable to broad range of clients ? Actively deployed in many of Google?s services ? System provides highperformance storage system on a large scale ? Selfmanaging ? Thousands of servers ? Millions of ops/second ? Multipl
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