The DBAL OCI8 driver places the "(SERVER=POOLED)" directive in the wrong place. To illustrate, when the "pooled" option is given to the driver options the following TNS connect descriptor is build:
However the correct TNS connect descriptor is:
Also, the pooled option is missing in the PDO Oracle driver.
See this page for more info: http://docs.oracle.com/cd/B28359_01/server.111/b28310/manproc004.htm