This article is coming from TechPortal, thanks to the original author.

Check out our tips on:

• memcached
• mod_cache
• mod_expires
• Apache KeepAlive
• APC
• Alternative session storage
• GZip
• MySQLTuner
• and a bonus security tip!

Memcached

Memcached is a distributed memory caching system that stores data retrieved from the database (or other data source) in memory, allowing repeat reads to retrieve the data from memory rather than needing to query the database again, greatly increasing the speed of web applications.

The first thing to do is install the memcache daemon and client libraries:

root# apt-get update
root# apt-get install memcached php5-memcache

To check if memcache is running, you can use the following command:

root# ps -ef | grep memcached

You should ensure that the localhost has been added to the configuration, this can be done using grep as shown here:

root# grep 127.0.0.1 /etc/memcached.conf

This should output -l 127.0.0.1 if localhost is included in the configuration. If not, add this line to the configuration and restart memcached:

root# echo '-l 127.0.0.1' >> /etc/memcached.conf
root# /etc/init.d/memcached restart
root# /etc/init.d/apache2 restart

You need to create a PHP configuration file to include the module, which on a Debian-based system should be in/etc/php5/conf.d/memcache.ini:

extension=memcache.so

Magento itself can also be configured to utilise some memcache optimisations built into the software. The following XML should be added to the /var/www/app/etc/local.xml file once it has been generated:

 <config>
     <global>
         ...
         <cache>
             <backend><![CDATA[memcached]]></backend><!-- apc / memcached / xcache / empty=file -->
             <slow_backend><![CDATA[database]]></slow_backend>
             <memcached><!-- memcached cache backend related config -->
                 <servers><!-- any number of server nodes can be included -->
                     <server>
                         <host><![CDATA[127.0.0.1]]></host>
                         <port><![CDATA[11211]]></port>
                         <persistent><![CDATA[1]]></persistent>
                         <weight><![CDATA[1]]></weight>
                         <timeout><![CDATA[10]]></timeout>
                         <retry_interval><![CDATA[10]]></retry_interval>
                         <status><![CDATA[1]]></status>
                     </server>
                 </servers>
                 <compression><![CDATA[0]]></compression>
                 <cache_dir><![CDATA[]]></cache_dir>
                 <hashed_directory_level><![CDATA[]]></hashed_directory_level>
                 <hashed_directory_umask><![CDATA[]]></hashed_directory_umask>
                 <file_name_prefix><![CDATA[]]></file_name_prefix>
             </memcached>
         </cache>
     </global>
     ...
 </config>

Apache mod_cache

The Apache mod_cache module allows Apache to cache content on disk or in memory, thus decreasing page load times. Caching for dynamic sites such as ecommerce needs to be approached with some caution; the cache may become invalid and thus customers may receive stale content. To enable mod_cache perform the following steps:

root# a2enmod cache
root# a2enmod disk_cache
root# a2enmod mem_cache

Enable disk caching in the disk_cache.conf configuration file by uncommenting the CacheEnable line in /etc/apache2/mods-available/disk_cache.conf. Make sure you remember to restart apache after doing this.

There is also a utility you can install which will clear the disk cache, the following code sample shows how to install and run it:

root# apt-get install apache2-utils
root# htcacheclean -d30 -n -t -p /var/cache/apache2/mod_disk_cache -l 100M -i

This will clean our cache directory every 30 minutes and make sure that it will not get bigger than 100MB. You can tune these settings to fit your particular site needs.

Apache mod_expires

Well-written browser software will keep a cache of the webpages a user visits. Each webpage should have a content expiry header directive that tells the browser when the cache expires. If this header is not correctly set then the browser will re-request the content from source with every page hit. In order to ensure that the Magento pages have the correct content expiry in the header, you can add the following block to Magento’s .htaccess file:

<ifmodule mod_expires.c>
    ExpiresActive On
    ExpiresDefault "access plus 1 month"
</ifmodule>

Apache KeepAlive

The Apache KeepAlive functionality allows the TCP connection between a client and the server to remain open, allowing multiple requests to be served over the same connection. This can decrease page load times particularly on webpages with lots of images since it removes the overhead of having multiple connections opened. To use this functionality, edit the /etc/apache2/apache2.conf, find the KeepAlive entries, and make sure they are enabled as follows:

KeepAlive On
KeepAliveTimeout 2

This will enable the KeepAlive feature; the timeout parameter is in units of seconds.

PHP APC

PHP APC is an Alternative PHP Cache that caches the byte-compiled PHP code, which means that repeat requests to the same PHP script should not need to be recompiled before being served, which will increase performance. This is a pear module, but also has some system dependencies, so to install it we run the following:

root# apt-get install apache2-threaded-dev php5-dev php-pear make gpp
root# pecl install apc

The APC configuration file should be created, and on the debian system the path would be /etc/php5/conf.d/apc.ini. We place the following lines into this file:

extension=apc.so
apc.shm_size=256
apc.num_files_hint=10000
apc.user_entries_hint=10000
apc.max_file_size=5M

Also make sure that Magento is using APC for caching by editing /var/www/app/etc/local.xml and add the following somewhere inside the <global> tags:

<config>
        <global>
                …
                <cache>
                        <backend>apc</backend>
                        <prefix>alphanumeric</prefix>
                </cache>
                ….
        </global>
        ...
</config>

To verify if APC is installed, we can check if the output of phpinfo includes reference to it, by running the following command from the CLI:

root# php -r 'phpinfo();' | grep 'apc'

Database Session Storage

Typically, database servers are less utilised than web servers. Performance can usually be improved by moving session handling from the web server filesystem into the database server. Magento asks you whether you prefer a file or database session save type, but this is very easy to change in the XML. Open up /var/www/app/etc/local.xml, locate the <session_save> tags, and change the value so it looks like this (the default is <![CDATA[files]]>):

<session_save><![CDATA[db]]></session_save>

Another alternative is to use memcache for storing the sessions – this isn’t as persistent as the database store, but may be faster:

<session_save><![CDATA[memcache]]></session_save>

You can add details of your memcache server in the session save path:

<session_save_path><![CDATA[tcp://127.0.0.1:11211?persistent=1&weight;=2&timeout;=10&retry;_interval=10]]></session_save_path>

GZip Compression

Web pages can be compressed using GZip between the server and the client, reducing the amount of data that needs to be transferred. Although the act of compressing and decompressing adds a performance overhead there is usually a net gain in reducing the amount of traffic especially for large pages. To use GZip compression, enable the mod_deflatemodule in Apache, and add the following to the vhost for the site:

<ifmodule mod_deflate.c>
        SetOutputFilter DEFLATE
        # Netscape 4.x has some problems...
        BrowserMatch ^Mozilla/4 gzip-only-text/html
        # Netscape 4.06-4.08 have some more problems
        BrowserMatch ^Mozilla/4\.0[678] no-gzip
        # MSIE masquerades as Netscape, but it is fine
        BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
        # Don't compress images
        SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png)$ no-gzip dont-vary
        # Make sure proxies don't deliver the wrong content
        Header append Vary User-Agent env=!dont-vary
</ifmodule>

MySQLTuner

A final tool to consider for performance improvement is MySQLTuner. MySQLTuner is a Perl script which analyses your database and gives recommendations which variables you should adjust in my.cnf to increase performance. This can really help to get the database, often a performance bottleneck for these types of applications, performing as well as possible without needing expensive hardware upgrades. To install and run this utility, simply do:

bash$ wget http://mysqltuner.com/mysqltuner.pl
bash$ perl mysqltuner.pl

You see some recommendations for which variables could be changed to improve performance, it is best to make changes incrementally and one at a time so you can see how they affect the performance of the database

Bonus Security Tip: Changing the Admin URL

Although not an actual performance issue, you can improve security by changing the default URL from ‘admin’ to something more obscure, such as ’5i8FNvHg’. This will decrease the probability that a malicious user will hit upon your admin log-in page by guessing that the admin site is located at yourdomain.com/admin/, or that automated scripts scanning for Magento admin pages will find it.
To change the admin address you first need to stop Apache and clear the cache:

root# /etc/init.d/apache2 stop
root# rm -rf /var/www/var/cache/*
root# rm -rf /var/www/var/session/*

Then open up the /var/www/app/etc/local.xml file, locate the <frontName> tag, and change the ‘admin’ part it to something a lot more random, eg:

              <frontName><![CDATA[gJpf2VK5]]></frontName>

Then set Apache running again (bearing in mind your site will be down for the duration of this operation!):

root# /etc/init.d/apache2 start

Read all about it here.

Handy Commands

As many things in *nix environments tend to be, managing your DNS server may seem just a bit more complicated than necessary.

• rndc is the DNS control utility, used to reload your DNS configuration or restart your DNS server
• launchctl enables you to launch services such as DNS as a daemon.

If you don’t want to show TAX in the checkout cart, go to app/design/frontend/base/default/template/tax/checkout, and in tax.phtml find the lines:

To set and show how many items are left in stock, do the following:

Open app/design/frontend//default/template/catalog/product/view.html

Add the following code to the page where you want to render the available stock message.

<div></div>
<div>
	<!--inv-qty-->
	<?php
	$__manStock = $_product->getStockItem()->getManageStock();
	$__invAmt = (int)Mage::getModel('cataloginventory/stock_item')->loadByProduct($_product)->getQty();
	if ($__manStock > 0)
		{
		echo $this->__("Only $__invAmt Available in Stock");
		}
?>
	</div>
<div></div>

Make sure to set Magento to not manage inventory. On the individual product under the “Inventory” tab using the “Manage Stock” option, un-check “Use Config Settings” and set it to “Yes”. Remember to set the QTY to the amount you have in stock. Make sure to add to your CSS File the styling you want to for the inventory-qty class

Original post at http://www.studio1909.com/2009/10/18/magento-show-quantities/

It worked excellent for our site!

1. Edit app/code/core/Mage/Catalog/Helper/Product/Compare.php and change the following code:

public function getAddUrl($product)
{
return $this->_getUrl(’catalog/product_compare/add’, $this->_getUrlParams($product));
}

to:

public function getAddUrl($product)
{
//return $this->_getUrl(’catalog/product_compare/add’, $this->_getUrlParams($product));
return false;
}

2. Edit ./app/design/frontend/base/default/layout/catalog.xml (if you are using a different Magento theme, enter its name instead of default) and change the following code:

<block type=”catalog/product_compare_sidebar” before=”cart_sidebar” name=”catalog.compare.sidebar” template=”catalog/product/compare/sidebar.phtml”/>

to:

<!– <block type=”catalog/product_compare_sidebar” before=”cart_sidebar” name=”catalog.compare.sidebar” template=”catalog/product/compare/sidebar.phtml”/> –>

3. Flush the Magento cache from your Magento admin area->System->Cache Management.

(http://kb.siteground.com/article/How_to_disable_the_Compare_products_functionality.html)

open clsAWStats.php

find @ line ~195

htmlspecialchars(urldecode(trim($arrData[$iIndexItem][$iIndexAttr])))

and add remove_sc … like this

remove_sc(htmlspecialchars(urldecode(trim($arrData[$iIndexItem][$iIndexAttr]))))

now go to the end of the file an add this function (before the ?> tag )

function remove_sc($data) {
return preg_replace(“/[^a-zA-Z0-9\:\/.-_:;]/”,”,$data);
}

Original post found at http://www.jawstats.com/community/thread119, thanks to the poster, this solutions worked perfect for me!

DEVICE=eth0:0 <–
ONBOOT=yes
BOOTPROTO=static
IPADDR=xxx.xxx.xxx.xxx
NETMASK=255.255.254.0
GATEWAY=xxx.xxx.xxx.xxx
BROADCAST=xxx.xxx.xxx.255

restart network (/etc/init.d/network reload)

All explained here:

http://www.magentocommerce.com/wiki/4_-_themes_and_template_customization/css/unordered_list_work_correctly

From: http://yoursite.com/new.html

To: http://yoursite.com/old.html

Do the following in Magento to create the appropriate pemanent redirect:

1. Navigate to Catalog > Url Rewrite Management
2. Click the “Add Urlrewrite” button
3. Select “Custom” from the “Create Urlrewrite” drop-down menu
4. The “Urlrewrite Information” form would be:

ID Path: new.html

Request Path: new.html

Target Path: old.html

Redirect: Permanent(301)

Magento Error
There has been an error processing your request
Exception printing is disabled by default for security reasons.
Error log record number: 793079871864

Solution
If you get the above error in Magento, try the following solution:
1) In your File Manager (or FTP client), or if you are like me on the commandline, go to your Magento folder. (/var/www/errors)
2) Rename file “errors/local.xml.sample” to “errors/local.xml”.

Now, you will see the detailed error while accessing Magento (instead of the above default error).

It is recommended to rename again to local.xml.sample, when you’re done!