150 lines
5.2 KiB
Groff
150 lines
5.2 KiB
Groff
.TH MEMCACHED 1 "April 11, 2005"
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.SH NAME
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memcached \- high-performance memory object caching system
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.SH SYNOPSIS
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.B memcached
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.RI [ options ]
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.br
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.SH DESCRIPTION
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This manual page documents briefly the
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.B memcached
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memory object caching daemon.
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.PP
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.B memcached
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is a flexible memory object caching daemon designed to alleviate database load
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in dynamic web applications by storing objects in memory. It's based on
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libevent to scale to any size needed, and is specifically optimized to avoid
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swapping and always use non-blocking I/O.
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.br
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.SH OPTIONS
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These programs follow the usual GNU command line syntax. A summary of options
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is included below.
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.TP
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.B \-s <file>
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Unix socket path to listen on (disables network support).
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.TP
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.B \-a <perms>
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Permissions (in octal format) for Unix socket created with \-s option.
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.TP
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.B \-l <ip_addr>
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Listen on <ip_addr>; default to INADDR_ANY. This is an important option to
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consider as there is no other way to secure the installation. Binding to an
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internal or firewalled network interface is suggested.
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.TP
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.B \-d
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Run memcached as a daemon.
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.TP
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.B \-u <username>
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Assume the identity of <username> (only when run as root).
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.TP
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.B \-m <num>
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Use <num> MB memory max to use for object storage; the default is 64 megabytes.
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.TP
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.B \-c <num>
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Use <num> max simultaneous connections; the default is 1024.
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.TP
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.B \-R <num>
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This option seeks to prevent client starvation by setting a limit to the
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number of sequential requests the server will process from an individual
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client connection. Once a connection has exceeded this value, the server will
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attempt to process I/O on other connections before handling any further
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request from this connection. The default value for this option is 20.
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.TP
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.B \-k
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Lock down all paged memory. This is a somewhat dangerous option with large
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caches, so consult the README and memcached homepage for configuration
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suggestions.
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.TP
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.B \-p <num>
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Listen on TCP port <num>, the default is port 11211.
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.TP
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.B \-U <num>
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Listen on UDP port <num>, the default is port 11211, 0 is off.
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.TP
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.B \-M
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Disable automatic removal of items from the cache when out of memory.
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Additions will not be possible until adequate space is freed up.
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.TP
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.B \-r
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Raise the core file size limit to the maximum allowable.
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.TP
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.B \-f <factor>
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Use <factor> as the multiplier for computing the sizes of memory chunks that
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items are stored in. A lower value may result in less wasted memory depending
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on the total amount of memory available and the distribution of item sizes.
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The default is 1.25.
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.TP
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.B \-n <size>
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Allocate a minimum of <size> bytes for the item key, value, and flags. The
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default is 48. If you have a lot of small keys and values, you can get a
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significant memory efficiency gain with a lower value. If you use a high
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chunk growth factor (\-f option), on the other hand, you may want to increase
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the size to allow a bigger percentage of your items to fit in the most densely
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packed (smallest) chunks.
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.TP
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.B \-C
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Disable the use of CAS (and reduce the per-item size by 8 bytes).
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.TP
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.B \-h
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Show the version of memcached and a summary of options.
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.TP
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.B \-v
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Be verbose during the event loop; print out errors and warnings.
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.TP
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.B \-vv
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Be even more verbose; same as \-v but also print client commands and
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responses.
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.TP
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.B \-i
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Print memcached and libevent licenses.
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.TP
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.B \-P <filename>
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Print pidfile to <filename>, only used under \-d option.
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.TP
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.B \-t <threads>
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Number of threads to use to process incoming requests. This option is only
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meaningful if memcached was compiled with thread support enabled. It is
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typically not useful to set this higher than the number of CPU cores on the
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memcached server. The default is 4.
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.TP
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.B \-D <char>
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Use <char> as the delimiter between key prefixes and IDs. This is used for
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per-prefix stats reporting. The default is ":" (colon). If this option is
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specified, stats collection is turned on automatically; if not, then it may
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be turned on by sending the "stats detail on" command to the server.
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.TP
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.B \-L
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Try to use large memory pages (if available). Increasing the memory page size
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could reduce the number of TLB misses and improve the performance. In order to
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get large pages from the OS, memcached will allocate the total item-cache in
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one large chunk. Only available if supported on your OS.
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.TP
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.B \-B <proto>
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Specify the binding protocol to use. By default, the server will
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autonegotiate client connections. By using this option, you can
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specify the protocol clients must speak. Possible options are "auto"
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(the default, autonegotiation behavior), "ascii" and "binary".
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.TP
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.B \-I <size>
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Override the default size of each slab page. Default is 1mb. Default is 1m,
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minimum is 1k, max is 128m. Adjusting this value changes the item size limit.
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Beware that this also increases the number of slabs (use -v to view), and the
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overal memory usage of memcached.
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.br
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.SH LICENSE
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The memcached daemon is copyright Danga Interactive and is distributed under
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the BSD license. Note that daemon clients are licensed separately.
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.br
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.SH SEE ALSO
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The README file that comes with memcached
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.br
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.B http://www.danga.com/memcached
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.SH AUTHOR
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The memcached daemon was written by Anatoly Vorobey
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.B <mellon@pobox.com>
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and Brad Fitzpatrick
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.B <brad@danga.com>
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and the rest of the crew of Danga Interactive
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.B http://www.danga.com
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.br
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