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MEMCACHED(1)                                                                                    MEMCACHED(1)



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 <file>
              Unix socket path to listen on (disables network support).

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

       -l <ip_addr>
              Listen  on  <ip_addr>; default to INADDR_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.

       -R <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 han-dling handling
              dling any further request from this connection. The default value for this option is 20.

       -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, 0 is off.

       -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.

       -n <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 the use of CAS (and reduce the per-item size by 8 bytes).

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

       -I <size>
              Override the default size of each slab page. Default is 1mb. Default is 1m, minimum is 1k, max
              is  128m.  Adjusting  this value changes the item size limit.  Beware that this also increases
              the number of slabs (use -v to view), and the overal memory usage of memcached.

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

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
       http://www.danga.com/memcached

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 http://www.danga.com



                                               April 11, 2005                                   MEMCACHED(1)