- memcached : High Performance, Distributed Memory Object Cache server package.
- perl-Cache-Memcached : Perl client (library) to work with memcached server.
- python-memcached : Perl client (library) to work with memcached server.
- php-pecl-memcache : PHP extension to work with the Memcached server.
WARNING! These examples only works with RHEL / CentOS Linux version 6.x or above. For RHEL 5.x and older version use memcached source code installation method.Task: Install memcached
Open a terminal or login to remote server using ssh client. Type the following yum command to install the same:# yum install memcached.x86_64 php-pecl-memcache.x86_64Sample outputs:
Loaded plugins: product-id, rhnplugin, subscription-manager
Updating certificate-based repositories.
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package memcached.x86_64 0:1.4.4-3.el6 will be installed
--> Processing Dependency: libevent-1.4.so.2()(64bit) for package: memcached-1.4.4-3.el6.x86_64
---> Package php-pecl-memcache.x86_64 0:3.0.5-3.el6 will be installed
--> Processing Dependency: /usr/bin/pecl for package: php-pecl-memcache-3.0.5-3.el6.x86_64
--> Processing Dependency: /usr/bin/pecl for package: php-pecl-memcache-3.0.5-3.el6.x86_64
--> Running transaction check
---> Package libevent.x86_64 0:1.4.13-1.el6 will be installed
---> Package php-pear.noarch 1:1.9.4-4.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
memcached x86_64 1.4.4-3.el6 rhel-x86_64-server-6 68 k
php-pecl-memcache x86_64 3.0.5-3.el6 rhel-x86_64-server-6 60 k
Installing for dependencies:
libevent x86_64 1.4.13-1.el6 rhel-x86_64-server-6 66 k
php-pear noarch 1:1.9.4-4.el6 rhel-x86_64-server-6 393 k
Transaction Summary
================================================================================
Install 4 Package(s)
Total download size: 587 k
Installed size: 0
Is this ok [y/N]: y
Downloading Packages:
(1/4): libevent-1.4.13-1.el6.x86_64.rpm | 66 kB 00:00
(2/4): memcached-1.4.4-3.el6.x86_64.rpm | 68 kB 00:00
(3/4): php-pear-1.9.4-4.el6.noarch.rpm | 393 kB 00:00
(4/4): php-pecl-memcache-3.0.5-3.el6.x86_64.rpm | 60 kB 00:00
--------------------------------------------------------------------------------
Total 2.4 MB/s | 587 kB 00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Warning: RPMDB altered outside of yum.
Installing : 1:php-pear-1.9.4-4.el6.noarch 1/4
Installing : libevent-1.4.13-1.el6.x86_64 2/4
Installing : memcached-1.4.4-3.el6.x86_64 3/4
Installing : php-pecl-memcache-3.0.5-3.el6.x86_64 4/4
Installed products updated.
Installed:
memcached.x86_64 0:1.4.4-3.el6 php-pecl-memcache.x86_64 0:3.0.5-3.el6
Dependency Installed:
libevent.x86_64 0:1.4.13-1.el6 php-pear.noarch 1:1.9.4-4.el6
Complete!
How Do I Configure Memcached Server?
Edit /etc/sysconfig/memcached file, enter:# vi /etc/sysconfig/memcachedSample outputs:
PORT="11211"For busy servers you need to increase the values as follows:
USER="memcached"
MAXCONN="1024"
CACHESIZE="64"
OPTIONS="
- MAXCONN: Use 1024 max simultaneous connections; the default is 1024. For busy server increase this number as per requirements.
- CACHESIZE: Use 64 MB memory max to use for object storage; the default is 64 megabytes. For busy server you can set it to 512MB or 1GB (1024).
- OPTIONS: You can set server IP address (listen on address) here so that apache/php/nginx based serer can connect to the server. By default it is set 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 firewalled network interface is suggested.
PORT="11211"
USER="memcached"
MAXCONN="4096"
CACHESIZE="512"
OPTIONS="-l 192.168.1.15"
How Do I Start / Stop / Restart Memcached Server?
Type the following commands:# /etc/init.d/memcached start
# /etc/init.d/memcached stop
# /etc/init.d/memcached restart
# /etc/init.d/memcached statusOR run a System V init script using service command
# /sbin/service memcached start
# /sbin/service memcached stop
# /sbin/service memcached restart
# /sbin/service memcached statusHow Do I Verify That Memcached is Running and Working?
Type the following command to see if it is running or not:# pgrep memcached
# netstat -tulpn | grep :11211Sample outputs:
tcp 0 0 192.168.1.15:11211 0.0.0.0:* LISTEN 24964/memcachedUse the memcached-tool to get general stats:
udp 0 0 192.168.1.15:11211 0.0.0.0:* 24964/memcached
# memcached-tool 192.168.1.15:11211 statsSample outputs:
#192.168.1.15:11211 Field Value
accepting_conns 1
auth_cmds 0
auth_errors 0
bytes 5481902
bytes_read 8242409
bytes_written 26023492
cas_badval 0
cas_hits 0
cas_misses 0
cmd_flush 0
cmd_get 9042
cmd_set 4469
conn_yields 0
connection_structures 48
curr_connections 47
curr_items 3197
decr_hits 0
decr_misses 0
delete_hits 6
delete_misses 112
evictions 0
get_hits 7490
get_misses 1552
incr_hits 0
incr_misses 0
limit_maxbytes 536870912
listen_disabled_num 0
pid 24964
pointer_size 64
rusage_system 0.149977
rusage_user 0.043993
threads 4
time 1327395688
total_connections 171
total_items 3226
uptime 198
version 1.4.4
How Do I Configure Firewall To Protect My Memcached Server?
Make sure iptables only allows access to your own servers. Edit /etc/sysconfig/iptables and append the following rules or add it as follows to your shell scripts:See our RHEL / CentOS firewall tutorial here and here for more information about setting up firewall.
## add to your shell script ##
## assumption default INPUT policy is set to DROP ##
## only accept connection to tcp/udp port 11211 if ip is between 192.168.1.10 and 192.168.1.15 ##
iptables -A INPUT -p tcp --destination-port 11211 -m state --state NEW -m iprange --src-range 192.168.1.10-192.168.1.15 -j ACCEPT
iptables -A INPUT -p udp --destination-port 11211 -m state --state NEW -m iprange --src-range 192.168.1.10-192.168.1.15 -j ACCEPT
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