Introduction

Memcached is a high-performance, distributed caching system. It is often used to speed up dynamic database-driven websites by caching data and objects in memory to reduce the number of times the database must be read.

Installing memcached

shahid@shahid-laptop:~$ sudo apt-get install memcached
shahid@shahid-laptop:~$ sudo apt-get install php5-memcache

After installing these two packages next step is to configure memcached.conf file. ( /etc/memcached.conf )Memcached.conf

After that edit the memecached.ini file. ( /etc/php5/apache2/conf.d/memcache.ini )

A sample memcache.ini file

; uncomment the next line to enable the module
extension=memcache.so
[memcache]
memcache.dbpath="/var/lib/memcache"
memcache.maxreclevel=0
memcache.maxfiles=0
memcache.archivememlim=0
memcache.maxfilesize=0
memcache.maxratio=0
session.save_handler = memcache
session.save_path = "tcp://192.168.1.1:11211?weight=1,tcp://192.168.1.2:11211"

There are some situations where you want to store instances of memcache on two servers. On this situaltion you want to set ’session.save_path’ as in the above example as comma separated.After that start memcached

shahid@shahid-laptop:~$ memcached -d   ==> Start memcache as a background process

shahid@shahid-laptop:~$ memcached -vv ==> Start memcached as a foreground process

For testing memcached you can start memcached using -vv option . If you start memcached using -vv option you can see stroing session on memcache on the terminal.

shahid@shahid-laptop:~$ memcached -vv
slab class   1: chunk size     96 perslab 10922
slab class   2: chunk size    120 perslab  8738
slab class   3: chunk size    152 perslab  6898
slab class   4: chunk size    192 perslab  5461
slab class   5: chunk size    240 perslab  4369
slab class   6: chunk size    304 perslab  3449
slab class   7: chunk size    384 perslab  2730
slab class   8: chunk size    480 perslab  2184
slab class   9: chunk size    600 perslab  1747
slab class  10: chunk size    752 perslab  1394
slab class  11: chunk size    944 perslab  1110
slab class  12: chunk size   1184 perslab   885
slab class  13: chunk size   1480 perslab   708
slab class  14: chunk size   1856 perslab   564
slab class  15: chunk size   2320 perslab   451
slab class  16: chunk size   2904 perslab   361
slab class  17: chunk size   3632 perslab   288
slab class  18: chunk size   4544 perslab   230
slab class  19: chunk size   5680 perslab   184
slab class  20: chunk size   7104 perslab   147
slab class  21: chunk size   8880 perslab   118
slab class  22: chunk size  11104 perslab    94
slab class  23: chunk size  13880 perslab    75
slab class  24: chunk size  17352 perslab    60
slab class  25: chunk size  21696 perslab    48
slab class  26: chunk size  27120 perslab    38
slab class  27: chunk size  33904 perslab    30
slab class  28: chunk size  42384 perslab    24
slab class  29: chunk size  52984 perslab    19
slab class  30: chunk size  66232 perslab    15
slab class  31: chunk size  82792 perslab    12
slab class  32: chunk size 103496 perslab    10
slab class  33: chunk size 129376 perslab     8
slab class  34: chunk size 161720 perslab     6
slab class  35: chunk size 202152 perslab     5
slab class  36: chunk size 252696 perslab     4
slab class  37: chunk size 315872 perslab     3
slab class  38: chunk size 394840 perslab     2
slab class  39: chunk size 493552 perslab     2
<3 server listening
<7 new client connection
<7 get 190c562b24186ff47914309b3ceaab95
>7 END
<7 set 190c562b24186ff47914309b3ceaab95 0 1440 0
>7 STORED
<7 connection closed.
<7 new client connection
<7 get 8c1f38e6f02939cea6a6563049e216c8
>7 END
<8 new client connection
<8 get 7925615c1ab9933cb33af0121881a82b
>8 END

Another method for checking whether memcached was enamble or not is to check the phpinfo() function. In the phpinfo page should contain memcache module.