Scaling the MySQL database for high-availability and clustering is an activity that can take many forms.
This week, memcached vendor Schooner debuted its new Active Cluster for MySQL. Schooner first came into the market with a hardware-based solution for memcached -- an open source distributed system for caching content. Schooner has now moved to a software model, which is where the Active Cluster solution comes into play.
"Active Cluster adds what we think is a unique solution for replication and failover, maximizing the availability of MySQL with super high performance," Jerry Rudisin, CEO of Schooner Information Technology, told InternetNews.com.
The Active Cluster solution includes the Schooner flash-optimized implementation of MySQL Enterprise database. One of the key attributes of the Active Cluster solution is that it performs fully synchronous replication for MySQL databases as opposed to asynchronous replication.
"The problem with asynchronous replication is that by its nature the other nodes are behind by minutes or potentially hours," Schooner CTO John Busch told InternetNews.com "We have fully synchronous replication and we have a license from Oracle for MySQL and InnoDB, and what we do is we heavily modify those technologies to be able to fully scale up with cores and use flash memory."
Busch added that Schooner also enhances MySQL by replicating data from master to slave nodes as database transactions are occurring. He noted that Active Cluster does not commit a transaction until the action has been replicated to all of the slave nodes.
"So at any point in time, all of the slaves have exactly the same state," Busch said. "If a master fails, any slave can immediately take over and we can do a complete failover in a matter of seconds."
With the recent MySQL 5.5 update from Oracle, a new semi-synchronous replication capability was included. Busch noted that in his view, semi-synchronous doesn't go far enough.
Busch explained that the way semi-synchronous works is it uses a mechanism where, at the MySQL layer, a log is generated for every transaction, which is then communicated to slaves.
"Semi-synchronous replication waits for one of the slaves to receive and process the log file before it is committed," Busch said. "It has a very large impact on the latency for the transaction, and the net throughput is less than a quarter of Schooner Active Cluster."
Though Oracle's MySQL 5.5 semi-synchronous has a latency impact, Busch noted that it does have a positive impact on reliability. He said it helps to prevent databases from losing data, even though it has a performance penalty.
Overall, Schooner is supportive of Oracle's efforts with MySQL. Rudisin noted that Oracle has been a good partner of Schooner, and Oracle also certifies their compatibility.
"There was some concern from users about the future of MySQL, but Oracle is still fully invested and they seem quite serious about MySQL and seeing the market grow," Rudisin said.