The new native mySQL driver for PHP has several advantages: better performance and better logging and statistics. Last weeks we have seen occasional “Lost connection to Mysql server” PDO exceptions which were unrelated to CPU load, I/O, mem usage, slow DB queries or persistent connections. With this upgrade we rule out the possibility of an incompatible mysqlclient library. And we will have better debug information!
As a side result, PHPMyAdmin is upgraded from version 3 to 4.