| 1 | .TH MEMCACHED 1 "April 11, 2005" |
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| 2 | .SH NAME |
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| 3 | memcached \- high-performance memory object caching system |
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| 4 | .SH SYNOPSIS |
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| 5 | .B memcached |
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| 6 | .RI [ options ] |
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| 7 | .br |
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| 8 | .SH DESCRIPTION |
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| 9 | This manual page documents briefly the |
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| 10 | .B memcached |
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| 11 | memory object caching daemon. |
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| 12 | .PP |
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| 13 | .B memcached |
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| 14 | is a flexible memory object caching daemon designed to alleviate database load |
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| 15 | in dynamic web applications by storing objects in memory. It's based on |
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| 16 | libevent to scale to any size needed, and is specifically optimized to avoid |
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| 17 | swapping and always use non-blocking I/O. |
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| 18 | .br |
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| 19 | .SH OPTIONS |
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| 20 | These programs follow the usual GNU command line syntax. A summary of options |
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| 21 | is included below. |
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| 22 | .TP |
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| 23 | .B \-s <file> |
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| 24 | Unix socket path to listen on (disables network support). |
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| 25 | .TP |
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| 26 | .B \-a <perms> |
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| 27 | Permissions (in octal format) for Unix socket created with -s option. |
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| 28 | .TP |
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| 29 | .B \-l <ip_addr> |
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| 30 | Listen on <ip_addr>; default to INDRR_ANY. This is an important option to |
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| 31 | consider as there is no other way to secure the installation. Binding to an |
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| 32 | internal or firewalled network interface is suggested. |
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| 33 | .TP |
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| 34 | .B \-d |
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| 35 | Run memcached as a daemon. |
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| 36 | .TP |
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| 37 | .B \-u <username> |
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| 38 | Assume the identity of <username> (only when run as root). |
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| 39 | .TP |
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| 40 | .B \-m <num> |
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| 41 | Use <num> MB memory max to use for object storage; the default is 64 megabytes. |
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| 42 | .TP |
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| 43 | .B \-c <num> |
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| 44 | Use <num> max simultaneous connections; the default is 1024. |
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| 45 | .TP |
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| 46 | .B \-k |
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| 47 | Lock down all paged memory. This is a somewhat dangerous option with large |
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| 48 | caches, so consult the README and memcached homepage for configuration |
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| 49 | suggestions. |
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| 50 | .TP |
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| 51 | .B \-p <num> |
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| 52 | Listen on TCP port <num>, the default is port 11211. |
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| 53 | .TP |
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| 54 | .B \-U <num> |
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| 55 | Listen on UDP port <num>, the default is 0, off. |
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| 56 | .TP |
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| 57 | .B \-M |
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| 58 | Disable automatic removal of items from the cache when out of memory. |
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| 59 | Additions will not be possible until adequate space is freed up. |
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| 60 | .TP |
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| 61 | .B \-r |
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| 62 | Raise the core file size limit to the maximum allowable. |
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| 63 | .TP |
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| 64 | .B \-b |
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| 65 | Run a managed instanced (mnemonic: buckets)\n". |
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| 66 | .TP |
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| 67 | .B \-f <factor> |
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| 68 | Use <factor> as the multiplier for computing the sizes of memory chunks that |
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| 69 | items are stored in. A lower value may result in less wasted memory depending |
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| 70 | on the total amount of memory available and the distribution of item sizes. |
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| 71 | The default is 1.25. |
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| 72 | .TP |
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| 73 | .B \-n <size> |
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| 74 | Allocate a minimum of <size> bytes for the item key, value, and flags. The |
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| 75 | default is 48. If you have a lot of small keys and values, you can get a |
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| 76 | significant memory efficiency gain with a lower value. If you use a high |
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| 77 | chunk growth factor (-f option), on the other hand, you may want to increase |
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| 78 | the size to allow a bigger percentage of your items to fit in the most densely |
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| 79 | packed (smallest) chunks. |
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| 80 | .TP |
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| 81 | .B \-h |
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| 82 | Show the version of memcached and a summary of options. |
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| 83 | .TP |
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| 84 | .B \-v |
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| 85 | Be verbose during the event loop; print out errors and warnings. |
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| 86 | .TP |
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| 87 | .B \-vv |
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| 88 | Be even more verbose; same as \-v but also print client commands and |
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| 89 | responses. |
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| 90 | .TP |
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| 91 | .B \-i |
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| 92 | Print memcached and libevent licenses. |
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| 93 | .TP |
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| 94 | .B \-P <filename> |
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| 95 | Print pidfile to <filename>, only used under -d option. |
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| 96 | .TP |
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| 97 | .B \-t <threads> |
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| 98 | Number of threads to use to process incoming requests. This option is only |
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| 99 | meaningful if memcached was compiled with thread support enabled. It is |
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| 100 | typically not useful to set this higher than the number of CPU cores on the |
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| 101 | memcached server. The default is 4. |
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| 102 | .TP |
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| 103 | .B \-D <char> |
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| 104 | Use <char> as the delimiter between key prefixes and IDs. This is used for |
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| 105 | per-prefix stats reporting. The default is ":" (colon). If this option is |
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| 106 | specified, stats collection is turned on automatically; if not, then it may |
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| 107 | be turned on by sending the "stats detail on" command to the server. |
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| 108 | .TP |
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| 109 | .B \-L |
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| 110 | Try to use large memory pages (if available). Increasing the memory page size |
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| 111 | could reduce the number of TLB misses and improve the performance. In order to |
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| 112 | get large pages from the OS, memcached will allocate the total item-cache in |
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| 113 | one large chunk. Only available if supported on your OS. |
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| 114 | .br |
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| 115 | .SH LICENSE |
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| 116 | The memcached daemon is copyright Danga Interactive and is distributed under |
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| 117 | the BSD license. Note that daemon clients are licensed separately. |
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| 118 | .br |
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| 119 | .SH SEE ALSO |
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| 120 | The README file that comes with memcached |
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| 121 | .br |
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| 122 | .B http://www.danga.com/memcached |
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| 123 | .SH AUTHOR |
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| 124 | The memcached daemon was written by Anatoly Vorobey |
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| 125 | .B <mellon@pobox.com> |
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| 126 | and Brad Fitzpatrick |
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| 127 | .B <brad@danga.com> |
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| 128 | and the rest of the crew of Danga Interactive |
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| 129 | .B http://www.danga.com |
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| 130 | .br |
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