# What is Memcached?

Memcached is a general-purpose distributed memory caching system. It is often used to speed up dynamic database-driven websites by caching data and objects in RAM to reduce the number of times an external data source (such as a database or API) must be read.

Memcached's APIs provide a very large hash table distributed across multiple machines. When the table is full, subsequent inserts cause older data to be purged in least recently used order. Applications using Memcached typically layer requests and additions into RAM before falling back on a slower backing store, such as a database.

> [wikipedia.org/wiki/Memcached](https://en.wikipedia.org/wiki/Memcached)

# How to use this image

```console
$ docker run --name my-memcache -d memcached
```

Start your memcached container with the above command and then you can connect you app to it with standard linking:

```console
$ docker run --link my-memcache:memcache -d my-app-image
```

The memcached server information would then be available through the ENV variables generated by the link as well as through DNS as `memcache` from `/etc/hosts`.

How to set the memory usage for memcached

```console
$ docker run --name my-memcache -d memcached memcached -m 64
```

This would set the memcache server to use 64 megabytes for storage.

For infomation on configuring your memcached server, see the extensive [wiki](https://code.google.com/p/memcached/wiki/NewStart).
