1MEMCACHED(1) General Commands Manual MEMCACHED(1)
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6 memcached - high-performance memory object caching system
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9 memcached [options]
10
12 This manual page documents briefly the memcached memory object caching
13 daemon.
14 memcached is a flexible memory object caching daemon designed to alle‐
16 viate database load in dynamic web applications by storing objects in
17 memory. It's based on libevent to scale to any size needed, and is
18 specifically optimized to avoid swapping and always use non-blocking
19 I/O.
20
22 These programs follow the usual GNU command line syntax. A summary of
23 options is included below.
24 -l <ip_addr>
26 Listen on <ip_addr>; default to INDRR_ANY. This is an important
27 option to consider as there is no other way to secure the
28 installation. Binding to an internal or firewalled network
29 interface is suggested.
30 -d Run memcached as a daemon.
32 -u <username>
34 Assume the identity of <username> (only when run as root).
35 -m <num>
37 Use <num> MB memory max to use for object storage; the default
38 is 64 megabytes.
39 -c <num>
41 Use <num> max simultaneous connections; the default is 1024.
42 -k Lock down all paged memory. This is a somewhat dangerous option
44 with large caches, so consult the README and memcached homepage
45 for configuration suggestions.
46 -p <num>
48 Listen on TCP port <num>, the default is port 11211.
49 -U <num>
51 Listen on UDP port <num>, the default is port 11211.
52 -M Disable automatic removal of items from the cache when out of
54 memory. Additions will not be possible until adequate space is
55 freed up.
56 -r Raise the core file size limit to the maximum allowable.
58 -f <factor>
60 Use <factor> as the multiplier for computing the sizes of memory
61 chunks that items are stored in. A lower value may result in
62 less wasted memory depending on the total amount of memory
63 available and the distribution of item sizes. The default is
64 1.25.
65 -s <size>
67 Allocate a minimum of <size> bytes for the item key, value, and
68 flags. The default is 48. If you have a lot of small keys and
69 values, you can get a significant memory efficiency gain with a
70 lower value. If you use a high chunk growth factor (-f option),
71 on the other hand, you may want to increase the size to allow a
72 bigger percentage of your items to fit in the most densely
73 packed (smallest) chunks.
74 -h Show the version of memcached and a summary of options.
76 -v Be verbose during the event loop; print out errors and warnings.
78 -vv Be even more verbose; same as -v but also print client commands
80 and responses.
81 -i Print memcached and libevent licenses.
83 -P <filename>
85 Print pidfile to <filename>, only used under -d option.
86 -t <threads>
88 Number of threads to use to process incoming requests. This
89 option is only meaningful if memcached was compiled with thread
90 support enabled. It is typically not useful to set this higher
91 than the number of CPU cores on the memcached server.
92 -D <char>
94 Use <char> as the delimiter between key prefixes and IDs. This
95 is used for per-prefix stats reporting. The default is ":"
96 (colon). If this option is specified, stats collection is turned
97 on automatically; if not, then it may be turned on by sending
98 the "stats detail on" command to the server.
99
101 The memcached daemon is copyright Danga Interactive and is distributed
102 under the BSD license. Note that daemon clients are licensed sepa‐
103 rately.
104
106 The README file that comes with memcached
107 http://www.danga.com/memcached
108
110 The memcached daemon was written by Anatoly Vorobey <mellon@pobox.com>
111 and Brad Fitzpatrick <brad@danga.com> and the rest of the crew of Danga
112 Interactive http://www.danga.com
113 April 11, 2005 MEMCACHED(1)