If a Couchbase Server node is starting up for the first time, it creates whatever DB files necessary and begin serving data immediately. However, if there is already data on disk (likely because the node rebooted or the service restarted) the node needs to read all of this data off of disk before it can begin serving data. This is called “warmup”. Depending on the size of data, this can take some time.

When starting up a node, there are a few statistics to monitor. Use the cbstats command to watch the warmup stats:

cbstats localhost:11210 warmup

The following statistics are of particular interest when monitoring the warmup.

ep_warmup_thread

This is the overall indication of whether or not warmup is still running. Look for values: running and complete.

ep_warmup_state

This describes which phase of warmup is currently running. Look for values: loading keys, loading access log, and done.

• When ep_warmup_state is loading keys, compare ep_warmup_key_count (current number) with ep_warmup_estimated_key_count (target number).
• When ep_warmup_state is loading access log, compare ep_warmup_value_count (current number) with ep_warmup_estimated_value_count (target number).