World of *Nix

From last few months i am working to optimize our somewhereinblog.net server, because right now we are getting huge amount of hits everyday (1,00,000 + hits). In this series i will describe the tricks that i learned 🙂

On my first post of this searies i will talk about ETag. Before disable this, first we need to know what is ETags. From wikipedia:

An ETag (entity tag) is an HTTP response header returned by an HTTP/1.1 compliant web server used to determine change in content at a given URL. When a new HTTP response contains the same ETag as an older HTTP response, the contents are determined to be the same without further downloading. The header is useful for intermediary devices that perform caching, as well as for client web browsers that cache results. One method of generating the ETag is based on the last modified time of the file and the size of the file.

In certain situations, ETags may not improve the performance of a web application. For instance, some ETag generation schemes incorporate the file’s inode on the system. The file’s inode is unique to the file only on one specific machine. If a site has multiple servers, each with its own copy of the file (i.e. load balancing), then a user’s request for the same file may get served by a different machine. In that case, the inode will almost certainly be different and, if it is used to generate the ETag, it will cause the file to be re-downloaded.

So, this is not always helpfull for all type of sites. Always remember, if you are not using anything, you should not enable or kept enable on server.

Apache by default enable this ETags. We need to disable this to get better performance. Here i am describing the steps for debian and ubuntu linux.

We will take help from mod_header to disable ETags, so first we need to enable the mod_header (apache module)

sudo a2enmod header

sudo /etc/init.d/apache2 restart

this command will enable mod_header. Now open /etc/apache2/apache2.conf with your faviourate browser.

sudo nano /etc/apache2/apache2.conf

then paste the under given code to this apache2.conf file

Header unset ETag
FileETag None

now restart the apache2, and check if it working or not. If every thing OK, then you will not see the etags anymore 🙂

For better understanding i am giving you 2 screenshots.

Before ETag disable

After ETag disable:

If you don’t have root access to server, you still can do this from .htaccess , just copy that code to .htaccess instate of apache conf file.

Ask me if you have any question or problem about ETag.

today i passed some time tune my ubuntu gutsy (7.10). at the time of searching on the google i found www.medibuntu.org :). from that site:

Medibuntu (Multimedia, Entertainment & Distractions In Ubuntu) is a repository of packages that cannot be included into the Ubuntu distribution for legal reasons (copyright, license, patent, etc).

their package collection is so interesting. they have:

• acrobat reader
• w32codecs (also w64codecs)
• googleearth
• skype
• etc 🙂

isn’t it interesting  ?

before getting this site, i was really missing my favourite “w32codecs”

to use this repository you have to run these commands (it’s too simple)

first get the repository address:

sudo wget http://www.medibuntu.org/sources.list.d/gutsy.list -O /etc/apt/sources.list.d/medibuntu.list

then add the gpg key to trusted keyring (so that you will not get warning each time you do something with apt)

wget -q http://packages.medibuntu.org/medibuntu-key.gpg -O- | sudo apt-key add - && sudo apt-get update

too simple !!


thanks www.medibuntu.org for there hard work , to make life more easy :)

imagemagick is one of the best library to work with image. recently i have to install it to our production server. here is what i did:

$ apt-get install imagemagick

it downloads the package and all it’s dependences from debian/ubuntu repository, and installed. now i have to install the support of php (as our product running on php)

$ apt-get install php5-imagick

then i restarted the apache server to take effect this new package installation. if your using php4 then the package name should be php4-imagick

$ /etc/init.d/apache2 restart

that’s all 🙂

if you need imagemagick for your ruby , you can install the librmagick-ruby package.

**if this post doesn’t answer ur question, please post it in comment, i will try to help as much as possible. thanks for ur time.

Here i am going to describe how to enable mod_rewrite in apache2.2 -specaily for debian.

In default installion of apache2.2 on debian never enable mod_rewrite default. So you may need to enable .

First install the apache2.2 with this command :
debian user please use “su” before start this process
ubuntu user please use “sudo su” before start this process

apt-get install apache2 (it will install apache 2.2)

on current debian system you can enable mod_rewrite with simple command

a2enmod rewrite

old style, you can skip this portion

now use locate to find if the mod_rewrite.so is availble on your server

updatedb
locate mod_rewrite.so


it will found in “/usr/lib/apache2/modules”

new apache follow some folders to enable and disable mods.
so now do this:

cd /etc/apache2/mods-enabled
touch rewrite.load
gedit rewrite.load (you may use any editor to edit this file)

now paste this following line

LoadModule rewrite_module /usr/lib/apache2/modules/mod_rewrite.so

end of old style

Then edit /etc/apache2/sites-available/default or /etc/apache2/sites-available/000-default (check which one available on your system)

Find the following

Options Indexes FollowSymLinks MultiViews
AllowOverride None
Order allow,deny
allow from all

and change it to

Options Indexes FollowSymLinks MultiViews
AllowOverride all
Order allow,deny
allow from all

and finally restart Apache

/etc/init.d/apache2 restart
or
service apache2 restart

OK, you done 😀

don’t forget to comment, if it works or not.

thanks.

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