Требования
You need to install librrd first to be able to use PECL/rrd. Most common option
is using of librrd-dev package from your favourite linux distro.
PECL/rrd is tested with librrd 1.4.3, older or newer versions might or might not
work for you.
PECL/rrd installation is tested with PHP 5.3.2 or newer.
Внимание
Librrd and hence extension itself aren't mostly thread safe. There are many
global and shared states in librrd. It can be dangerous use this extension
in multi threaded environments like Apache2 mpm worker.
If there are many parallel requests, one request can change some global
librrd state of other runnig requests.