memcached is a flexible memory object caching daemon designed to alleviate database load in dynamic web applications by storing objects in memory. It's based on libevent to scale to any size needed, and is specifically optimized to avoid swapping and always use non-blocking I/O.

-l <ip_addr>

Listen on <ip_addr>; default to INDRR_ANY. This is an important option to consider as there is no other way to secure the installation. Binding to an internal or firewalled network interface is suggested.

-d

Run memcached as a daemon.

-u <username>

Assume the identity of <username> (only when run as root).

-m <num>

Use <num> MB memory max to use for object storage; the default is 64 megabytes.

-c <num>

Use <num> max simultaneous connections; the default is 1024.

-k

Lock down all paged memory. This is a somewhat dangerous option with large caches, so consult the README and memcached homepage for configuration suggestions.

-p <num>

Listen on TCP port <num>, the default is port 11211.

-U <num>

Listen on UDP port <num>, the default is port 11211.

-M

Disable automatic removal of items from the cache when out of memory. Additions will not be possible until adequate space is freed up.

-r

Raise the core file size limit to the maximum allowable.

-f <factor>

Use <factor> as the multiplier for computing the sizes of memory chunks that items are stored in. A lower value may result in less wasted memory depending on the total amount of memory available and the distribution of item sizes. The default is 1.25.

-s <size>

Allocate a minimum of <size> bytes for the item key, value, and flags. The default is 48. If you have a lot of small keys and values, you can get a significant memory efficiency gain with a lower value. If you use a high chunk growth factor (-f option), on the other hand, you may want to increase the size to allow a bigger percentage of your items to fit in the most densely packed (smallest) chunks.

-h

Show the version of memcached and a summary of options.

-v

Be verbose during the event loop; print out errors and warnings.

-vv

Be even more verbose; same as -v but also print client commands and responses.

-i

Print memcached and libevent licenses.

-P <filename>

Print pidfile to <filename>, only used under -d option.

-t <threads>

Number of threads to use to process incoming requests. This option is only meaningful if memcached was compiled with thread support enabled. It is typically not useful to set this higher than the number of CPU cores on the memcached server.

-D <char>

Use <char> as the delimiter between key prefixes and IDs. This is used for per-prefix stats reporting. The default is ":" (colon). If this option is specified, stats collection is turned on automatically; if not, then it may be turned on by sending the "stats detail on" command to the server.