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)