# memcached -u memcached -d -m 30 -l 127.0.0.1 -p 11211 You’ll notice there is “-l 127.0.0.1” in your command line. This tells memcached to only listen on the lo interface. If you want to access it from a remote machine, you need to remove this part of the command line.
You’ve pretty much got the answer to your first question already: the intent of ADD is to only work when a key doesn’t already exist, while SET is there to update the value, regardless of whether it already exists. If you’re familiar with SQL, it’s (roughly) like the difference between INSERT queries (ADD) and UPDATE … Read more
It has been a year since this question and I don’t know if you found your answer but I’m going to say your perception of “wasted” is wrong. Wasted memory is allocated in memory so it can not be used by another application, but it still is available for memcached. To simplify the explanation, assume … Read more
Depends on what you need, in general I think that: You should not care too much about performances. Redis is faster per core with small values, but memcached is able to use multiple cores with a single executable and TCP port without help from the client. Also memcached is faster with big values in the … Read more
As Mike said, you can look at the line including the “STAT bytes” to see memory usage: $ echo “stats” | nc -w 1 <host> <port> | awk ‘$2 == “bytes” { print $2″ “$3 }’
Disclaimer: You’d be mad to listen to me without doing a tonne of testing AND getting a 2nd opinion from someone qualified – I’m new to this game. The efficiency improvement idea proposed in this question won’t work. The main mistake that I made was to think that the order that the memcached stores are … Read more
This is a great question, something I have pondered over quite a bit. I will summarize my lessons learned: You can easily use Lucene/Solr in lieu of MongoDB for pretty much all situations, but not vice versa. Grant Ingersoll’s post sums it up here. MongoDB etc. seem to serve a purpose where there is no … Read more
Memcached client library was just recently released as stable. It is being used by digg ( was developed for digg by Andrei Zmievski, now no longer with digg) and implements much more of the memcached protocol than the older memcache client. The most important features that memcached has are: Cas tokens. This made my life … Read more
I use Ubuntu, and Debian mostly, so this answer is based on those, but I suspect the answer for other distros is largely the same. In /etc/memcached.conf — If it’s not in exactly the same place, a) I’d be surprised, and b) you could find it with locate # Start with a cap of 64 … Read more
This means the service was running at one time, but has crashed. When you start a service, it creates a “lock” file to indicate that the service is running. This helps avoid multiple instances of the service. When you stop a service, this lock file is removed. When a running service crashes, the lock file … Read more