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Perfsonar LS scalability issues

Perfsonar LS scalability issues. Common LS queries. The most common LS query will likely be: “find me the service_accesspoint for X” Samples: Find me the topology server for ESnet Find me all pSB MAs for community “LHC” Find me all pSB MAs with throughput data for host X

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Perfsonar LS scalability issues

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  1. Perfsonar LS scalability issues

  2. Common LS queries • The most common LS query will likely be: • “find me the service_accesspoint for X” • Samples: • Find me the topology server for ESnet • Find me all pSB MAs for community “LHC” • Find me all pSB MAs with throughput data for host X • Currently the last 2 queries all need to hit many hLSes. • This fundamentally can not scale! • Issues: Some hLS will be down, when to timeout?, very high latency to hLS on the other side of the planet, etc.

  3. Sample Performance Results • Find the topology server for ESnet • Queries only 1 hLS • Query time = 14 seconds • Find all pSB MAs with throughput data for host albu-pt1.es.net • Queries a total of 12 hLS • Total Query time = 110 seconds • Find all pSB MAs for community “LHC” • Queries a total of 26 hLS • Query time = 179 seconds

  4. Solution? • More data needs to be in (or “next to”) the gLS • See Martin’s proposed solution • I think it should be easy to answer queries like this using the gLS only: • Find all pSB MAs for community “LHC” • Other queries will be trickier, but should still be possible? • Find all pSB MAs with throughput data for host albu-pt1.es.net

  5. Fixing things • gLS architecture is fine and works for summarization and scalability • The problem is that the gLS doesn’t have service access points, which necessitates contacting each hLS in the current implementation • Putting SAPs in the gLS would reduce available summarization

  6. Solution Direction • The original model included other layers of LSes • Automatic creation of hierarchy is difficult • that’s basically why it was dropped in the evolution of the dLS architecture • We need a way to discover services without touching all hLSes • especially by each node

  7. Solution Space • Two solutions: • Index Services • Gather relevant information (servicing a particular query) and keep it up to date • Ex: All pSB MPs, all North American MPs • This would talk to all hLSs and refresh fairly periodically (pull model) • Domain Lookup Services • Large domains host DomLS

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