This is a regression !

Initially mentioned in https://support.zabbix.com/browse/ZBX-4635#comment-56147 but unfortunately was ignored.
Recently Rich poked me that the issue is still not created, so I'm creating it finally.

This regression appeared after ZBXNEXT-485 and visible starting from 2.0.0 stable release.

Some testing:

1. ./zabbix_agentd18 -p | grep vfs.dev
   vfs.dev.read[sda,operations] [u|1224452]
   vfs.dev.write[sda,sectors] [u|1563159382]

1. ./zabbix_agentd18 -V
   Zabbix Agent (daemon) v1.8.16rc1 (revision 31798) (20 August 2012)
   Compilation time: Dec 4 2012 21:15:15

1. ./zabbix_agentd20 -p | grep vfs.dev
   vfs.dev.read [u|1213712]
   vfs.dev.write [u|34578915]

1. ./zabbix_agentd20 -V
   Zabbix Agent (daemon) v2.0.4rc1 (revision 31099) (03 October 2012)
   Compilation time: Oct 26 2012 16:25:02

Testing two trunk revisions, see binary name:

1. ./zabbix_agentd22245 -p | grep vfs.dev
   vfs.dev.read[sda,operations] [u|1220934]
   vfs.dev.write[sda,sectors] [u|1562171832]

1. ./zabbix_agentd22246 -p | grep vfs.dev
   vfs.dev.read [u|1220934]
   vfs.dev.write [u|1562174268]

This has to be fixed, default values is very important.