zabbix 1.8 introduced a couple of changes with data reporting - most notably, linux cpu index starts now with 0 (as opposed to 1), and diskspace is returned in bytes, not in kb.

to make transitioning easier, there should be a configuration flag (zabbix16compat or something) that would make these checks behave like in 1.6 and before.

this way users could enable compat mode and upgrade agents slowly, then once all agents are upgraded, flip the flag in the agent config and in templates.