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WANdisco's CVS MultiSite



CVS MultiSite (http://www.wandisco.com) leverages WANdisco's unique replication technology to immediately synchronize CVS repositories connected over a wide area network (WAN). Users at every ...

CVS MultiSite (http://www.wandisco.com) leverages WANdisco's unique replication technology to immediately synchronize CVS repositories connected over a wide area network (WAN). Users at every location experience local area network (LAN) speed performance for both read and write operations. CVS MultiSite also provides continuous hot backup and self-healing capabilities that automate disaster recovery, so that downtime is virtually eliminated.



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    WANdisco's CVS MultiSite WANdisco's CVS MultiSite Presentation Transcript

      • Peer-to-peer architecture with no single point of failure.
      • Not master-slave or multi-master.
        • Repositories at every site are fully readable and writeable.
      • CVS repositories connected over a WAN synchronize automatically with each write operation.
      • Developers at all locations experience LAN speed performance for both read and write operations.
      • Built-in hot backup and automated disaster recovery features make third party solutions completely unnecessary.
      • Transparent implementation doesn’t change CVS behavior, so there’s no retraining.
      Key Features
      • Replicator implemented as a transparent network proxy at each site.
        • Normally installed on the same server as CVS at each location.
        • Listens on same port clients use to connect to CVS:
          • Default Port 2401.
          • SSH is also supported.
        • Client configurations don’t change.
        • No changes to CVS.
      • LAN-speed performance over a WAN results from a
      • combination of CVS MultiSite’s:
      • Active-active replication capability:
        • CVS servers become active nodes on a network.
        • Each node works cooperatively with its peers to agree on transaction ordering.
        • Each node’s repository becomes an exact replica of every other.
      • Quorum Configuration
        • Quorum based on distribution of users/activity across sites for best performance.
        • Only a quorum of nodes have to agree on transaction ordering.
      • Network Architecture
        • Minimizes number of WAN roundtrips and bandwidth usage.
      • How it works:
      • The replicator generates a proposal (header) for each write at its location and sends it to its peers.
        • The proposal contains a globally unique transaction id and other data used to determine if conflicts exist.
        • The proposal’s unique transaction id is used at every location to guarantee consistent transaction order.
      • Users experience LAN speed performance
        • Once agreement is received from a quorum of nodes, the write goes forward at the site where it originated.
        • No waiting for other sites to complete the write.
        • Agreement takes less than half a second between US and India over a typical E-1 line.
        • All reads are local and generate no WAN traffic.
      Active-Active Replication
    • Quorum Configuration
      • How it works:
      • Quorum configuration options:
        • Majority - Only 51% of nodes required to respond to proposal.
          • Distinguished Node – node used as tie-breaker with an even number of nodes
        • Singleton - The Distinguished Node is the quorum.
          • Ideal if one site has many more users and activity than others.
            • Superior performance at the quorum site.
          • Responses from remote nodes are not required at the Distinguished node
            • No WAN traffic generated for agreement process .
            • Writes get sent to other nodes after agreement process completes at distinguished node
        • Unanimous - Responses required from all nodes
      • Follow-the-sun quorum rotation
          • Optimizes performance for each region’s normal working hours.
    • Network Optimization
      • How it works:
      • Reduces network traffic and bandwidth usage and costs
      • All reads are local and generate no WAN traffic
      • Streaming on Persistent connection between servers
        • Connection pooling used for multiplexing
        • TCP 3-Way Handshake Eliminated
      • Uses WANdisco’s own protocol over the WAN
        • Eliminates normal CVS chattiness over the WAN
        • WAN roundtrip times are significantly reduced
      • Eliminates tag explosion problem
          • Only the tag command and the associated metadata is sent.
          • Other solutions send all of the tagged files as well.
    • Demo
    • Built-in Backup and Recovery
      • Active-Active replication delivers continuous hot backup by default.
      • CVS MultiSite leverages this to provide automated recovery.
        • Catch up from any other live node on restart after a network outage or server crash.
        • Maintains a database-like redo log/pending transaction journal for recovery.
        • Split brain is impossible.
      • Users can failover to another site’s CVS server while theirs is down and continue working.
      • Makes full 24X7 operation possible in a globally distributed environment.
        • Servers can be taken offline for maintenance without disrupting user access.
      • Third party disk mirroring solutions are completely unnecessary.
      • Server Versions Supported
        • CVS Server versions 1.11.17 to 1.11.21 are supported
      • Supported Clients
        • CVS command line, WinCVS, TortoiseCVS, SmartCVS, Eclipse and IntelliJ.
      • System Requirements
        • CVS MultiSite will run in any J2SE 1.5 or above compliant Java runtime environment. A minimum of 64 MB of RAM and 450MHz CPU is recommended for the server
      System Requirements
      • Unique technology allows distributed development teams to work as one at LAN-speed over a WAN, instead of working in silos.
      • Dramatically reduces development time and cost.
      • Peer-to-peer architecture with no single point of failure.
      • All servers can be monitored and administered from a single location.
      • Built-in continuous hot backup and self-healing capabilities eliminate risk in a disaster recovery scenario.
      • Makes full 24x7 operation possible in a distributed environment.
      • Transparent implementation eliminates retraining.
      • Most cost effective multi-site solution available for CVS.