Cluster Architectures / Server Backup¶
Virtual DataPort can operate within a cluster architecture to provide high availability and load balancing.
Typically, clustering architectures for Virtual DataPort operate as follows:
- An external load-balancing system distributes the requests received among a pool of Virtual DataPort servers.
- The load-balancing system detects when a server is not responding (using the so-called “server health check”). In this case, the load is distributed among the remaining servers.
- The clustering system detects when the server is available again (using the “health check”) and adds it to the pool.
The following clustering solutions have been tested with Virtual DataPort:
- Linux Virtual Server architecture, using Keepalive (KeepAlived. Health Checking for LVS & High Availability) to check whether a server is responding at any given time.
- Windows Network Load Balancing Tool. This is the clustering solution included in the Windows 2000 server family.
Virtual DataPort provides some features to make cluster architecture configuration easier:
- It provides a “Ping” script to check the status of Virtual DataPort servers. Although solutions such as Keepalive provide their own default implementations for “health-checking” an application, the Ping script detects failure situations that would not be detected by other solutions.
- It provides a utility to automatically replicate the metadata and the configuration of a Virtual DataPort server into a pool of other Virtual DataPort servers. This utility can also be used to schedule backup copies of the metadata of a Server.
- “Safe shut down mode”: when entering this mode, the Server does not accept new connections and it will not shut down until all the current queries finish. This allows you to remove a Server from the cluster without affecting external clients.
The following sections describe how to:
- Install the Denodo Tools: a set of tools that help building a cluster with several Virtual DataPort servers (see section Denodo Tools).
- Use the Ping script (see section How to Check If a Virtual DataPort Server Is Alive)
- Replicate the metadata of a Virtual DataPort server, to a group of servers (see section Using the Import/Export Scripts for Backup And/or Replication).