Product (4/5):
- Monitors hundreds of nodes running of a not to beefy vm.
- Easily extendable.
- Smooth upgrades. (Not automatic but well documented.)
- User interface is sometimes a little hard to understand. Not bad for a product the size of Zenoss but not perfect either.
- Lots of official documentation freely available covering most of what one needs to know.
- Forums were migrated to Jive a couple of years ago leaving lots of broken links.
- Nice and helpful community.
- Lots of contributed plugins a.k.a. ZenPacks. Examples
- Hardware health status on HP servers
- Oracle databases
- vmware ESX and ESXi
I did a lot of reading up front before implementing Zenoss and considered
- Zabbix,
- Hyperic,
- OpenNMS,
- Nagios
- agent-less architecture
- hp hardware monitoring almost out-of-the-box
- snmp trap handling.
However keep in mind that a full implementation might easily take weeks even for a skilled sysadmin, depending on the size of the monitored network, the status of the network (is snmp enabled? Who has to approve it? etc.)