track of a number of metrics and statistics about its own performance and
raises alarms when certain thresholds are exceeded. The system also protects
itself by rejecting requests that would cause it to exceed its critical
capacity limits. When the node is at capacity, new recordings are redirected to
other nodes (if available) or rejected and lost.
Since recording is
always considered to be the highest priority operation, MediaSense reserves a
certain amount of capacity specifically for that purpose, electing to reject
media output requests while still continuing to accept new recording requests.
Media output requests (such as live monitoring, playback, raw download and .mp4
or .wav conversion) result in 503 responses when the node is at capacity.
weight of various media is also considered for overload throttling. For
example, video takes significantly more capacity than audio.
Note however, that
these are overload protection mechanisms only; they are not intended to enforce
licensed or rated capacity. They reflect the levels at which the product has
been tested and they exist so that MediaSense nodes can protect themselves and
offer graceful service degradation in case of severe overuse.
It is still the
customer's responsibility to engineer his or her deployment such that the
overall rated node and cluster capacities are not exceeded.
protects itself with respect to media storage capacity. It raises alarms,
redirects new calls to other nodes (if available), prunes older recordings to
recover space (if permitted), and even drops existing calls (as a last resort)
in order to maintain the integrity of existing recordings.
The Real Time
Monitoring Tool (RTMT) provides a great deal of statistical information about
use levels and throttling activities for each node.