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OceanStore/Tapestry Toward Global-Scale, Self-Repairing, Secure and Persistent Storage. Anthony D. Joseph John Kubiatowicz Sahara Retreat, January 2003. OceanStore Context: Ubiquitous Computing. Computing everywhere: Desktop, Laptop, Palmtop Cars, Cellphones Shoes? Clothing? Walls?
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OceanStore/TapestryToward Global-Scale, Self-Repairing, Secure and Persistent Storage Anthony D. Joseph John Kubiatowicz Sahara Retreat, January 2003
OceanStore Context: Ubiquitous Computing • Computing everywhere: • Desktop, Laptop, Palmtop • Cars, Cellphones • Shoes? Clothing? Walls? • Connectivity everywhere: • Rapid growth of bandwidth in the interior of the net • Broadband to the home and office • Wireless technologies such as CMDA, Satelite, laser • Where is persistent data????
Canadian OceanStore Sprint AT&T IBM Pac Bell IBM Utility-based Infrastructure • Data service provided by storage federation • Cross-administrative domain • Pay for Service
versions Comet Analogy updates OceanStore Data Model • Versioned Objects • Every update generates a new version • Can always go back in time (Time Travel) • Each Version is Read-Only • Can have permanent name • Much easier to repair • An Object is a signed mapping between permanent name and latest version • Write access control/integrity involves managing these mappings
Inner-Ring Servers Second-Tier Caches Clients Multicast trees The Path of an OceanStore Update
GUID1 GUID2 GUID1 Enabling Technology: DOLR(Decentralized Object Location and Routing) DOLR
3 4 2 NodeID 0xEF97 NodeID 0xEF32 NodeID 0xE399 NodeID 0xEF34 NodeID 0xEF34 1 4 NodeID 0xEF37 NodeID 0xEF44 3 2 1 3 NodeID 0x099F 4 4 3 2 NodeID 0xE530 NodeID 0xEF40 3 NodeID 0xEF31 4 NodeID 0xE555 NodeID 0xEFBA 2 NodeID 0x0999 3 1 2 1 2 3 NodeID 0xE932 NodeID 0xFF37 NodeID 0x0921 NodeID 0xE324 1 Basic Tapestry MeshIncremental Prefix-based Routing
Stability under Faults • Instability is the common case….! • Small half-life for P2P apps (1 hour????) • Congestion, flash crowds, misconfiguration, faults • Must Use DOLR under instability! • The right thing must just happen • Tapestry is natural framework to exploit redundant elements and connections • Multiple Roots, Links, etc. • Easy to reconstruct routing and location information • Stable, repairable layer • Thermodynamic analogies: • Heat Capacity of DOLR network • Entropy of Links (decay of underlying order)
Single Node Tapestry Other Applications Application-LevelMulticast OceanStore Application Interface / Upcall API Routing Table&Object Pointer DB Dynamic NodeManagement Router Network Link Management Transport Protocols
It’s Alive! • Planet Lab global network • 98 machines at 42 institutions, in North America, Europe, Australia (~ 60 machines utilized) • 1.26Ghz PIII (1GB RAM), 1.8Ghz PIV (2GB RAM) • North American machines (2/3) on Internet2 • Tapestry Java deployment • 6-7 nodes on each physical machine • IBM Java JDK 1.30 • Node virtualization inside JVM and SEDA • Scheduling between virtual nodes increases latency
Segments of OceanStorewithin Sahara Retreat • Today (5:30pm – 6:00pm) • OceanStore Long-Term Archival Storage • Tomorrow morning session (8:30am-10:00am) • Tapestry status and deployment information
For more info:http://oceanstore.org • OceanStore vision paper for ASPLOS 2000 “OceanStore: An Architecture for Global-Scale Persistent Storage” • OceanStore Prototype (FAST 2003):“Pond: the OceanStore Prototype” • Tapestry algorithms paper (SPAA 2002):“Distributed Object Location in a Dynamic Network” • Upcoming Tapestry Deployment Paper (JSAC)“Tapestry: a Global-Scale Overlay for Rapid Service Deployment” • Probabilistic Routing (INFOCOM 2002): “Probabilistic Location and Routing” • Upcoming CACM paper (not until February): • “Extracting Guarantees from Chaos”