memcached - high performance memory object caching system
memcached [-l <ip-addr>] [-d] [-u <username>] [-m <num>] [-c <num>] [-k] [-L ] [-p <num>] [-U <num>] [-s <filename>] [-a <perms>] [-M] [-r] [-b] [-f <factor>] [-n <size>] [-h] [-v] [-vv] [-i] [-P <filename>] [-t <threads>] [-D <char>]
memcached(8) Administration Commands memcached(8)
NAME
memcached - high performance memory object caching system
SYNOPSIS
memcached [-l <ip-addr>] [-d] [-u <username>]
[-m <num>] [-c <num>] [-k] [-L ]
[-p <num>] [-U <num>] [-s <filename>]
[-a <perms>] [-M] [-r] [-b]
[-f <factor>] [-n <size>] [-h] [-v] [-vv] [-i]
[-P <filename>] [-t <threads>] [-D <char>]
DESCRIPTION
memcached is a flexible memory object caching daemon designed to alle-
viate database load in dynamic web applications by storing objects in
memory. It is based on libevent to scale to any size needed, and is
specifically optimized to avoid swapping and always use non-blocking
I/O. This man page documents briefly the memcached memory object
caching daemon.
OPTIONS
The options supported by the memcached command are described below.
-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
fire walled network interface is suggested.
-d Run memcached as a daemon.
-u <username> Assume the identity of <username> only when run as a
super user (root).
-m <num> Use the maximum <num> MB memory for object storage;
the default is 64 MB.
-c <num> Use the specified number of maximum simultaneous con-
nections; the default is 1024.
-k Lock down all paged memory.
Use this option with caution with large caches. For
information about the configuration suggestions, see
the README and the memcached home page.
-L Preallocate memory and use large memory pages if pos-
sible.
This option will preallocate cache memory for object
storage. See description of -m option for a specifi-
cation of the size of the memory. If supported by the
platform, large memory pages will be allocated. This
should reduce number of TLB misses and increase per-
formance.
-p <num> Listen on the TCP port <num>. The default port is
11211.
-U <num> Listen on the UDP port <num>. The default is 0, mean-
ing that the UDP protocol is disabled.
-s <filename> Unix socket path to listen on (disables listening sup-
port for TCP and UDP).
-a <perms> Permissions (in octal format) for Unix socket created
with -s option. Default value is 0700.
-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 allow-
able.
-b Run a managed instance.
-f <factor> Use this option to specify <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 avail-
able and the distribution of item sizes. The default
value is 1.25.
-n <size> Allocate a minimum of <size> bytes for the item key,
value, and flags. The default value is 48. If you have
a lot of small keys and values, you can get a signifi-
cant memory efficiency gain with a lower value. If you
use a high chunk growth factor, that is -f option, you
may want to increase the size to allow a bigger per-
centage of your items to fit in the most densely
packed smallest chunks.
-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 option but also print
client commands and responses.
-i Display memcached and libevent licenses.
-P <filename> Print pidfile to the specified file.
Note -
This option can be used only when mechached is run
as a daemon (-d option).
-t <threads> Number of threads to use to process incoming requests.
The default is 4. It is typically not useful to set
this much higher than the number of CPU cores on the
memcached server.
-D <char> Use the <char> as the delimiter between key prefixes
and IDs. This is used for per-prefix statistics
reporting. The default is : (colon). If this option
is specified, statistics collection is turned on auto-
matically; if not, then it can be turned on by sending
the stats detail on command to the server.
EXIT STATUS
The following exit values are returned:
0 command executed successfully
1 error in executing the command
SERVICE MANAGEMENT FACILITY
memcached package for Solaris (service/memcached) includes files neces-
sary to register with the Service Management Facility described in
SMF(7). The following procedure describes the steps to automate the
service management using memcached.
1. Add other parameters to be passed to the memcached service
instance.
example: specify the server to use 1024 MB of memory
example% svccfg
svc:> select memcached
svc:/application/database/memcached> setprop memcached/options=("-m" "1024")
svc:/application/database/memcached> quit
example% svcadm refresh memcached
Note -
The arguments cannot be passed as a single string because of a
limitation in svccfg.
2. Enable memcached .
example% svcadm enable memcached
The state of the service instance changes to online, and the
memcached service instance must be started:
example% svcs memcached
STATE STIME FMRI
online 1:19:15 svc:/application/database/memcached:default
3. To disable shutdown and automatic restart of memcached ser-
vice instance,
example% svcadm disable memcached
USER AUTHORIZATIONS
You can use RBAC(7) to authorize otherwise non-privileged users to man-
age memcached services. To let a user named myuser change memcached
value properties and manage memcached service states, add the following
line to /etc/user_attr:
myuser::::type=role;profiles=Memcached Administration,All
PACKAGE CONTENTS
The memcached package consists of the memcached server and man pages
for the server.
Client libraries can be made available by installing other packages.
The memcached server is based on the memcached open-source software
available from http://www.danga.com/memcached/.
SECURITY
When the memcached server is started, it listens for network requests
on a TCP port and/or a UDP port. It is important for the security of
the network that you protect this port, for example, by blocking access
to this port in a firewall.
The default TCP port number to use is 11211.
You may use the -p option to set another TCP port number. There is no
default UDP port number. You can use the -U option to set a UDP port
number.
If you are running memcached on a server with multiple network inter-
faces, you can restrict vulnerability by binding memcached to a single
interface by using the -l option.
Caution -
Note that memcached was designed for speed and not for security.
There is no authentication of requests that go in to the memcached
servers, and communication is not encrypted. The network that your
memcached servers and clients run within should be safe-guarded
against network attacks.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+-------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-------------------+
|Availability | service/memcached |
+---------------+-------------------+
|Stability | Uncommitted |
+---------------+-------------------+
SEE ALSO
libmemcached(3libmemcached)
Additional documentation (FAQ) can be found at http://www.eu.social-
text.net/memcached/index.cgi.
NOTES
LICENSE
The memcached daemon is copyright Danga Interactive and is distributed
under the BSD license. memcached clients are licensed separately.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from http://memcached.org/files/mem-
cached-1.4.35.tar.gz
Further information about this software can be found on the open source
community website at http://memcached.org/.
Solaris 11.4 20 Oct 2015 memcached(8)