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CoDeeN,Large Files, & CoDeploy KyoungSoo Park, Vivek Pai, Larry Peterson Princeton University
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What Is CoDeeN? Content Distribution Networks Web pages load faster if You’re contacting a nearby server That server isn’t overloaded The page is already in memory You use long-lived TCP connections right
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CoDeeN By The Numbers In operation ~10 months 150 nodes (~120 live) 6.5 million reqs/day 5 million “good” reqs/day about 300GB/day (estimate) 7K-20K unique IPs per 24 hours Over 600,000 unique IPs served
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Our “Strategy” Stay operational Build some credibility Exploit that + activity to branch out Involves doing sales pitches Tap into new consumers In particular, nonprofits, non-commercial
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What Most CDNs (want to) Serve
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But What About Big Files?
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How Big? 200 TeraBytes of data total Interviews: about 3.5GB each Files: average of 700MB each
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Problem: “Nobody” Handles 700MB CDNs designed for avg size 10KB 1MB = 100 files 700MB = 70,000 files Commercial disks ~ 100GB Our storage ~ 3GB
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New Problems Why not replicate less? You’re farther away Why not merge requests? client readahead slow client
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Our Approach AgentCDN Server Client file file0-1 file2-3 file4-5 file3-4 file1-2
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Low-Level HTTP Stuff GET name/ranges Header: blah HTTP/1.0 206 Partial Range: start-end/length Header: blah GET name Range: bytes ranges Header: blah HTTP/1.0 200 OK Content-length: piece length New-header: obj length egress ingress
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Benefits Transparent to client (no software) Server only needs byte-range support Every real server has it Will generate more log entries Can use/augment HTTP infrastructure Caching, redirection, etc Adding security controls Low incremental overhead Agent is about 300 semicolons CDN mods about 20 semicolons
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Dual-Use Technology Other one-to-many problems Node/experiment installs Software updates Push model instead of pull Solution? Build “master” script Push to nodes Nodes pull as needed
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CoDeploy Now in beta Small set of tools at source No (new) installation at target Needed tools at CoDeeN-hosting nodes Fun components Peer-review system of CoDeeN nodes Nearest CoDeeN finder Parallel ssh, scp
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What To Expect Next Will redeploy auto-rewriting service Akamai-like URL mangling Was in testing before December upgrade Tie rewriter into “hosting” service Make it simpler for provider to use CoDeeN
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More Info http://codeen.cs.princeton.edu/codeploy KyoungSoo Park kyoungso@cs.princeton.edu Vivek Pai vivek@cs.princeton.edu
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