MySQL/MariaDB-Galera是一套在 MySQL InnoDB 上面实现 Multi-master 且 synchronous replication 的系統。
MySQL/MariaDB-Galera 0.8发行说明：
So Galera 0.8 comes with many nice features:
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Works with MySQL 5.1 and MariaDB 5.1. The latest is
more interesting for us, as it is based on XtraDB. That means Galera supports the XtraDB storage engine. Support for multi-threaded slaves. Using custom scripts for node propagation. RSYNC method comes with the Galera distribution, and it is quite easy to add support for Percona Xtra
Backup to propagate nodes.
Why MySQL/MariaDB + Galera 0.8 is interesting? It allows to solve following problems:
A Real High Availability solution for systems based on InnoDB/XtraDB. The recommended setup is 3 nodes and you can add / remove nodes al
most transparently. It is possible to use it in traditional master-slave setups, but with big difference – with Galera with have Synchronous slaves. A transaction is not committed on the master until it is committed on the slave. That means no more slave delays. With parallel appl
ying on slaves, the latency of round-trip transactions should be in an acceptable range. It opens the possibility for active master – active master setups. You can write on both masters and do not worry about conflict resolution and get rid of those “slave is out of sync with master” pain-in-the-neck problems. Combining all above, now we can setup distributed replication systems with masters in different data centers. This provides a HA solution for MySQL setups in the Cloud. E.g. with
current state of MySQL EC2 setups suffer from lacking a good HA schema. With Galera, we can setup replication with the same availability and in different zones. Remember the recent and famous EC2 outage? Ha
ving masters in USA and Europe regions would solve this kind of problems. Scaling Writes. From benchmarks provided by the Galera team we may see a good scaling of throughput writing to several nodes