OLPC:Volunteer Infrastructure Group/Databases

VIG supports the operation of many services that back onto databases, and so these database systems are critical infrastructure. VIG applications use both MySQL and PostgreSQL database systems (RDBMS) for different applications. For example RT and Trac are currently hosted on PostgreSQL.

MySQL

For increased availability MySQL has master/slave replication (with binary logs), the more recent and advanced MySQL clustering technologies, and support for virtualization, proxying and load-balancing. Here's a link to the top of MySQL.com's High Availability (HA) documentation

Replication

MySQL replication is useful for keeping database tables in sync. A slave server is granted access to pull binlogs from a master server, and the slave does all of the work by pulling every change from the master and committing it. In typical server group configurations a master accepts all changes (writes) while read-only slaves serve read requests. Replication can also be used for backup. Two master/slave replications can also be set up to keep two (or more?) live servers in sync. Here is the upstream MySQL.com page on replication.

Clustering

MySQL also offers sophisticated clustering solutions that can group mutiple MySQL instances on a server, and then theseservers into groups and so on. Here's the start of MySQL'com's clustering documentation.

PostgreSQL

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