Gfarm is a distributed filesystem, generally used for large scale cluster computing. It's implemented in userland, and can be mounted by FUSE. It utilizes locality of a file to access a data node, and supports Globus GSI for Wide Area Network. Users can explicitly control file replica location on Gfarm. Gfarm can be used as an alternative storage system to HDFS for Hadoop, Samba, MPI-IO, and GridFTP. Monitoring via ZABBIX and Ganglia is also supported.
Zabbix/J is a framework for integrating Zabbix monitoring into Java applications. Zabbix is an "enterprise-class Open Source distributed monitoring solution" which provides telemetry and triggers across entire infrastructures. Zabbix/J makes it simple to expose metrics from your Java applications, giving them visibility as first class citizens in a Zabbix configuration.
Monitoring::Spooler is a handy queue manager for queueing and delivery of monitoring notifications. It is able to handle several groups of on-call personnel and provides an extensible plugin mechanism to connect it to virtually any remote service which provides some kind of API. It is designed to work nicely with App::Standby.