NAME

       memcached - high-performance memory object caching system

SYNOPSIS

       memcached [options]

DESCRIPTION

       This manual page documents briefly the memcached memory object caching daemon.

       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.

OPTIONS

       These programs follow the usual GNU command line syntax. A summary of options is  included
       below.

       -s, --unix-socket=<file>
              Unix socket path to listen on (disables network support).

       -A, --enable-shutdown
              Enable ascii "shutdown" command.

       -a, --unix-mask=<perms>
              Permissions (in octal format) for Unix socket created with -s option.

       -l, --listen=<addr>
              Listen  on <addr>; default to INADDR_ANY. <addr> may be specified as host:port.  If
              you don't specify a port number, the value you specified with -p or -U is used. You
              may  specify  multiple  addresses separated by comma or by using -l multiple times.
              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, --daemon
              Run memcached as a daemon.

       -u, --user=<username>
              Assume the identity of <username> (only when run as root).

       -m, --memory-limit=<num>
              Use <num> MB memory max to use for object storage; the default is 64 megabytes.

       -c, --conn-limit=<num>
              Use <num> max simultaneous connections; the default is 1024.

       -R, --max-reqs-per-event=<num>
              This  option seeks to prevent client starvation by setting a limit to the number of
              sequential requests the server will process from an individual  client  connection.
              Once  a  connection has exceeded this value, the server will attempt to process I/O
              on other connections before handling any further request from this connection.  The
              default value for this option is 20.

       -k, --lock-memory
              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, --port=<num>
              Listen on TCP port <num>, the default is port 11211. 0 means off.

       -U, --udp-port=<num>
              Listen on UDP port <num>, the default is port 0, which is off.

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

       -r, --enable-coredumps
              Raise the core file size limit to the maximum allowable.

       -f, --slab-growth-factor=<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.

       -n, --slab-min-size=<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.

       -C, --disable-cas
              Disable the use of CAS (and reduce the per-item size by 8 bytes).

       -h, --help
              Show the version of memcached and a summary of options.

       -v, --verbose
              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.

       -vvv   Be extremely verbose; same of the above and also print internal state transitions.

       -i, --license
              Print memcached and libevent licenses.

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

       -t, --threads=<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.
              Setting  a  high  number  (64  or  more)  of worker threads is not recommended. The
              default is 4.

       -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.

       -L, --enable-largepages
              Try to use large memory pages (if available). Increasing the memory page size could
              reduce the number of TLB misses and improve the performance. In order to get  large
              pages from the OS, memcached will allocate the total item-cache in one large chunk.
              Only available if supported on your OS.

       -b, --listen-backlog=<num>
              Set the backlog queue limit to <num> connections. The default is 1024.

       -B, --protocol=<proto>
              Specify the binding protocol to use.  By default,  the  server  will  autonegotiate
              client  connections.   By  using  this option, you can specify the protocol clients
              must speak.  Possible options are "auto" (the default,  autonegotiation  behavior),
              "ascii" and "binary".

       -I, --max-item-size=<size>
              Override the default size of each slab page. The default size is 1mb. Default value
              for this parameter is 1m, minimum is 1k, max is 1G (1024 * 1024 * 1024).  Adjusting
              this value changes the item size limit.

       -S, --enable-sasl
              Turn  on  SASL  authentication.  This  option  is  only meaningful if memcached was
              compiled with SASL support enabled.

       -F, --disable-flush-all
              Disables the "flush_all" command. The cmd_flush counter will increment, but clients
              will receive an error message and the flush will not occur.

       -X, --disable-dumping
              Disables the "stats cachedump" and "lru_crawler metadump" commands.

       -o, --extended=<options>
              Comma  separated list of extended or experimental options. See -h or wiki for up to
              date list.

       -V, --version
              print version and exit

LICENSE

       The memcached daemon is copyright Danga Interactive  and  is  distributed  under  the  BSD
       license. Note that daemon clients are licensed separately.

SEE ALSO

       The README file that comes with memcached
       https://www.memcached.org

AUTHOR

       The   memcached  daemon  was  written  by  Anatoly  Vorobey  <mellon@pobox.com>  and  Brad
       Fitzpatrick  <brad@danga.com>  and  the  rest   of   the   crew   of   Danga   Interactive
       https://www.danga.com

                                          April 11, 2005                             MEMCACHED(1)