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High Availability and DR Solutions High Availability and DR Solutions

While the PostgreSQL database is renowned for its robustness, reliability and emphasis on ensuring the safety and consistency of data, there are times when factors such as hardware and software failure, administration mishaps and disaster scenarios need to be correctly managed. This may require that a database replication solution be put in place to guard against known and unknown database issues.

The Fujitsu Supported PostreSQL (FSP) team has spent many years working with clients on the implementation of High Availability (HA) and Disaster Recovery (DR) solutions that stand up to the requirements of always-on, 24/7 operation.

From synchronous multi-site disaster recovery solutions to SAN-level replication, the FSP team can work with clients to advise on and customise HA/DR solutions to suit their specialised business requirements.

Some of the solutions supported by FSP include:

  • High-availability using synchronous replication

Synchronous replication guarantees that all changes made by a transaction are  transferred to remote standby nodes. This is an extension to the standard level of durability offered by a transaction commit.

When synchronous replication is requested, the transaction waits after commit until it receives confirmation that the transfer has been successful. This usually requires careful planning and location of standby servers to ensure applications perform adequately.

PostgreSQL allows application designers to specify the required durability level via replication. This can be specified for the system overall, or for individual transactions.

  • Slony-I PostgreSQL Replication

Slony-I is an asynchronous master-slave replication system which allows clients to maintain read-only almost-real-time replicas of their databases at a multitude of locations. Slony-I is an open source project which has received great support from the PostgreSQL community, and is the leading open source replication solution for PostgreSQL. Slony-I is under active development, powers large systems such as the .org registry, and is the perfect tool to use when looking to implement off-site, WAN-based HA/DR systems.

  • SAN-based replication solutions

The FSP team can architect and assist with HA/DR solutions which utilise shared storage on a SAN and clustering software such as RedHat Cluster Suite to provide high performance, hot standby master-slave database replication with zero downtime.

For disaster recovery, options such as off-site SAN replication are also available.