Skip to main content

How to make your mailserver faster ?


My mailserver was very slow when more than 10 users accessing it simultaneously. It uses squirrelmail as the front-end for webmail. As you know (or maybe don't know :P), squirrelmail is built using php and an administrator can extend its functionality via plugins. There's many good plugins to ease administrator's chore and also for users. php on a good side is a very powerful language but it is suffer when it has to open and execute many files. It has to recompile everytime the file is to be executed. This results in slower response because it has to do the same thing over and over again. But thank god I just found the solution. The solution is simple. Everytime the php file is compiled, the resulting binary is used whenever the file is fetched. This results in faster execution time and faster response. The term for this solution is php accelerator. There's many php accelerator out there but the one that gives large boost performance is eaccelerator formerly know as Turck MMCache. It is claimed as the fastest php accelerator out there. For time being I have installed Turck MMCache (the old version of eaccelerator) for I haven't found any Mandrake package of eaccelerator yet. This is what I installed on my mailserver box to make it faster.

1. php accelerator (Turck MMCache)
To speed up php execution.

2. caching-nameserver (BIND 9)
To speed up dns resolution.

3. imapproxy (http://www.imapproxy.org) -- updated : Sept 20,2005
To speed up connection to imap server by caching it.

4. chmod 1777 /var/spool/mail -- updated : Oct 18,2005
Speed up Squirrelmail access to mail and for some distro like Mandrake 10.x, it can prevent crash. (only for those who use mbox-style mail format)

Clever huh? If you know the theory of the details on how networked boxen connect and talk with each other, you also should know how to make it faster.

Cheers!

Comments

Popular posts from this blog

mplayer-gui error : Error in skin config file

After installing mplayer-gui package, I can't start it.

$ gmplayer MPlayer 1.1-4.8 (C) 2000-2012 MPlayer Team mplayer: could not connect to socket mplayer: No such file or directory Failed to open LIRC support. You will not be able to use your remote control. Error in skin config file on line 6: PNG read error in /usr/share/mplayer/skins/default/main Config file processing error with skin 'default'
After googling a bit, I found out that it was due to the png files in dir /usr/share/mplayer/skins/default. This is the default skin directory. To fix this error, I have to install ImageMagick package because I want to use the convert program to convert all of the png files to format png24. Thus, cd /usr/share/mplayer/skins/default; for FILE in *.png ; do sudo convert $FILE -define png:format=png24 $FILE ; done
Rerun gmplayer and all should be fine.
Have fun!
UPDATE (02-10-2017)

It doesn't work on Ubuntu 16.04 (xenial) but there's a workaround here.

You can update your syst…

Moving your mysql database to another hard disk

Recently, my server's only hard disk was almost full. I bought a new hard disk with bigger size and I decided to just add it as a second hard disk. Since I need to move it to the 2nd hard disk, I need to find a proper way to move the db with minimum downtime. So I googled around and found a solution.
First, I needed to format the 2nd hard disk and I chose xfs as the filesystem. I created 2 partitions using Linux's fdisk for this task. First partition is 10 GB and 2nd one is around 900 GB. That's approximately added up to 1 TB. Then I mounted the 2nd partition in current partition eg /media/hd2 as follows:
mount -t xfs /dev/sdb5 /media/hd2
where /dev/sdb5 is the partition and /media/hd2 is the mounting dir.
Stop mysql db before doing anything:
service mysql stop
Afterthat, I copied the entire db to newly mounted hard disk:
cp -rv /var/lib/mysql /media/hd2
It will take a while if you have huge databases.
Then, change the ownership of the dir to user and group of mysql:
chown -R mysql:…

Transparent proxy with squid 2.6

I have upgraded my squid from 2.5 STABLE13 to 2.6 STABLE18. Transparent proxy is setup differently in this version. You need this directives in squid.conf (usually in /etc or /usr/local/etc or /usr/local/squid/etc, check with your distro).

acl our_networks src 192.168.2.0/24 127.0.0.1
http_access allow our_networks
http_port 192.168.2.1:3128 transparent
always_direct allow all

where 192.168.2.1 is your proxy server IP address.


If you have flushed your iptables, create new rule:

iptables -t nat -A PREROUTING -i eth0 -p tcp –dport 80 -j REDIRECT –to-port 3128

where 3128 is the port where squid is running.
References:
http://www.deckle.co.za/squid-users-guide/Transparent_Caching/Proxy