Memcached

• Key Points
• Monitoring
• Diagrams
  • Memcached in AWS Clustered Web Services
  • Memcached in Multi-Datacenter Java Stack

Key Points

• simple key=value pairs in memory
• used as a cache to speed up web applications or other apps that put/get values to it
• put / get by key
• port 11211
• standalone individual daemon, non-clustered first generation NoSQL tech
• usually used on each web / app server to be used locally on that server only
• often to offload cache queries from things like RDBMS
• no authentication - restrict socket to listen on localhost loopback address for local server access only

• Memcached => Membase => Couchbase (2.0 Jan 2012)

See also Couchbase doc.

Monitoring

• check_memcached_key.pl - checks a specific key exists and optionally content matches against a given regex and/or number range thresholds
• check_memcached_stats.pl - checks the stats of a memcached instance
• check_memcached_write.pl - full API level unique write + read back check

See Couchbase Monitoring section too.

Diagrams

From the HariSekhon/Diagrams-as-Code repo:

Memcached in AWS Clustered Web Services

Memcached in Multi-Datacenter Java Stack

Partial port from private Knowledge Base page 2013+