Much of New Relic's software runs on FreeBSD, but for some Linux-based agents there are some challenges.
New Relic agents
New Relic supported the PHP agent on FreeBSD through version 184.108.40.206. With the release of version 220.127.116.11, FreeBSD support was no longer available. Older versions of the agent will still report data to the collector.
While FreeBSD was the supported OS, the agent may also run on other BSDs for x86 and amd64 architectures only. New Relic compiled the earler release packages on FreeBSD 7.3 or higher. Recommendation: Use FreeBSD 7.4 or higher; releases earlier than 7.3 are not supported.
PHP users may encounter the following error with FreeBSD 8:
/libexec/ld-elf.so.1: Shared object "libz.so.4" not found, required by "newrelic-daemon"
If you do, create a symlink from libz.so.4 to the actual version of libz.so you have installed.
Note: Some versions of PHP shipped with FreeBSD do not come with the LINKTHR build option enabled; if yours doesn't, change it and rebuild PHP. Otherwise the agent will cause your web server to hang when processing PHP requests.
The monitoring agent for New Relic Servers is a Linux binary, and it may run on *BSD using binary emulation. However, the statistic gathering methods the server monitor uses are totally irrelevant on BSD systems. If anything is reported, it will likely be wrong.