Tutorial by Examples

Client metrics cover the traffic between the client and the Varnish cache. sess_conn - Cumulative number of connections. client_req - Cumulative number of client requests. sess_dropped - Dropped connections because of a full queue. Monitor sess_conn and client_req to keep track of traffic vo...

Perhaps the most important performance metric is the hitrate. Varnish routes it's incoming requests like this: Hash, a cacheable request. This might be either hit or miss depending on the state of the cache. Hitpass, a not cacheable request. A hash with a miss and a hitpass will be fetched f...

You monitor the cached objects to see how often they expire and if they are "nuked". n_expired - Number of expired objects. n_lru_nuked - Last recently used nuked objects. Number of objects nuked (removed) from the cache because of lack of space. varnishstat -1 | grep "n_expire...

You need to keep track of some threads metrics to watch your Varnish Cache. Is it running out of OS resources or is it functioning well. threads - Number of threads in all pools. threads_created - Number of created threads. threads_failed - Number of times Varnish failed to create a thread. th...

There are a number of metrics describing the communication between Varnish and it's backends. The most important metrics here might be these: backend_busy - Number of http 5xx statuses recieved by a backend. With VCL you can configure Varnish to try another backend if this happens. backend_fail...