Uma coisa a ser lembrada ao configurar o jboss é que às vezes a melhor documentação está nos projetos para os componentes individuais. No caso de configurações de fonte de dados, sempre digo às pessoas para verificar os documentos do IronJacamar:http://www.ironjacamar.org/doc/userguide/1.0/en-US/html_single/
para o que você quer fazer, estas configurações devem funcionar:
<validation>
<valid-connection-checker class-name="org.jboss.jca.adapters.jdbc.extensions.postgres.PostgreSQLValidConnectionChecker"/>
<exception-sorter class-name="org.jboss.jca.adapters.jdbc.extensions.postgres.PostgreSQLExceptionSorter"/>
<!-- I don't know what this does but someone on my DevOps
team said to set it this way. :) -->
<validate-on-match>false</validate-on-match>
<!-- validate the connection using a background
thread rather than right before you try to use the connection -->
<background-validation>true</background-validation>
<!-- sets the frequency the background thread will check each connection.
The lower this setting, the quicker it will find a bad connection
but it will be more chatty sending the validations to the server -->
<background-validation-millis>60000</background-validation-millis>
<!-- fast fail will mark all the connections invalid as soon as
it finds a bad one. This will make it clear the pool quicker
if all connections are reset at once such as a restart. Fast
fail would be trouble though if you had a setup where the database
sometimes selectively kills a single connection, such as killing long
running queries. -->
<use-fast-fail>true</use-fast-fail>
</validation>
