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MEMCACHED(1)		    General Commands Manual		  MEMCACHED(1)

       memcached - high-performance memory object caching system

       memcached [options]

       This  manual page documents briefly the memcached memory	object caching

       memcached is a flexible memory object caching daemon designed to	 alle-
       viate  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

       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

       -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  ad-
	      dresses  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

       -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

       -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

       -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  op-
	      tion  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  im-
	      prove  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

       -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  op-
	      tions   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 in-
	      crement, but clients will	receive	an error message and the flush
	      will not occur.

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

       -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

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

       The README file that comes with memcached

       The memcached daemon was	written	by Anatoly Vorobey  <>
       and Brad	Fitzpatrick <> and the rest of the crew of Danga

				April 11, 2005			  MEMCACHED(1)


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