Multiple A DNS records and browser retries failover / redundancy

I wanted to know how firefox / chrome etc behave when there are two A DNS records for a website, and one of those IPs does not respond.  The use-case for this is to have the same website hosted in two locations, and when one server/network becomes offline that the other one can take over.

I couldn’t find any up to date info about this so I thought I’d just do some tests and compile my own info. Test case used only two A records for the same hostname.

NOTE: If the connection returns an error sooner, presumably these browsers will failover faster. The test here was a complete drop of traffic with no TCP reset/icmp error coming back from the first attempted IP.

Using multiple DNS A records is a plausible failover mechanism in modern browsers!

PROBLEM: Browsers seem to switch between IPs after a period of inactivity (even just a few minutes).  If your site requires state, you will need to make state be stored inside the browser (preferably) or some kind of shared state system between servers.

Pros:
Multi-server failover is relatively easy, and fast in modern browsers
Traffic is balanced between both locations

Cons:
If one A record server stops responding, the user may experience a delay when loading the site
If one A record server stops responding while the user was already on the site, they may see an error until they reload the page.
If state required, need to store in browser or shared state system

End of Life – PHP version 4 webhosting

PHP version 4 was officially retired 8 years ago and no longer receives any kind of official patches or support. To preserve functionality for our resellers who have customer services requiring PHP v4 we have maintained our own patch subset for PHP v4 since 2008.

Our volume of PHPv4 websites has now reached a low enough level that it no longer makes business sense to maintain our PHPv4 Webhosting services. Effective 1 August 2017, we will no longer offer / support PHPv4 websites.

We recommend to all customers to either upgrade their websites to PHPv5, PHPv6, or PHPv7. You can select the different version from our webhosting panel to temporarily change your php version to see how it may affect your website. We would recommend trying PHP 5.2.

If you need help with migration we recommend placing a RackCorp support ticket. Any sites still operating on PHPv4 will be automatically upgraded to PHPv5.2 on August 1st. Please note there is a VERY HIGH chance that this will break sites that were built for PHPv4.

RackCorp welcomes Melbourne to our global network

We are pleased to announce high-availability premium virtual servers via in Metronode’s recently completed Melbourne 2 Data Centre located in Victoria, Australia.

This data centre is unique in that not only does it allow us to offer hosting and server products in a location geographically convenient to Southern Australian users, but provides very high security and energy efficiency features.

Our Melbourne point of presence is ideal for customers in Victoria, South Australia and especially Tasmania who are seeking the best latency and speeds to their websites.

RackCorp’s in-house developed management system and global network

Combined with Metronode’s Tier 3 Rating means our Melbourne site is ideal for customers who require a higher level of redundancy and reliability

What Exactly is a Tier 3 rating?

A specification defined by both the Uptime institute and ANSI/TIA of USA which contains formal requirements for the design of a data centre.

The rating covers items such as

• Site space and layout
• Physical infrastructure such as cabling, site security, access control and power.
• Reliability rating of the sites infrastructure
• Environmental efficiency and Management, both internal and external

Very few data centres in Australia are Tier 3 rated as a number are just designed to best-practise rather than an industry recognised specification.

Energy Efficiency – the future key to reliable web hosting

A commonly cited metric to measure a data centre is its PUE (power utilization efficiency) rating. The lower the PUE, the more efficient the cooling, better the reliability with less chance of outages and the lower the energy costs.

Metronode’s unique ‘BladeRoom’ data hall design and Melbourne’s cool climate enable a very low PUE of 1.1, one of the lowest possible and best in Australia.

RackAdmin – RackCorp’s in-house developed web hosting and network management platform

One of the key principles behind our company is emphasis on in-house custom developed solutions based on open source software.

A bespoke open source foundation provides us with

• Maximum reliability as bugs can be patched before official fixes are available
• Maximum performance thanks to streamlined and lean code
• Maximum flexibility and extensibility to meet our customers and our own specific needs
• Minimising cost and licensing which helps keeps prices competitive

These principles form the basis on which is why we built RackAdmin, the backbone of our company since foundation. A custom, in house developed management platform which provides end-user account management, option and service provisioning including reseller management and geo-location and automated billing. All within a slick and easy to use interface and an API.

Rackadmin provides is a streamlined,slick and easy to use solution to manage your web hosting needs

Read more »

Apache 2 + FastCgi + PHP 5 compile / build

Building the three of these is fairly easy, but a bit tricky if you’re used to how it worked in previous versions of Apache or PHP.  Please note that we install everything into prefix trees and use a tool called graft to manage the versions.  If you simply install your versions into default locations, you can probably leave out anything to do with prefix=, and top_dir.  We also download all install archives into /usr/local/PKG_BUILD.

Anyway to get started, the first trick is to build Apache 2 first by itself.  Here is an example:

cd /usr/local/PKG_BUILD
tar -xvzf httpd-2.2.8.tar.gz
cd httpd-2.2.8
./configure –prefix=/usr/local/PACKAGES/httpd-2.2.8 –enable-file-cache –enable-cache –enable-deflate –enable-mime-magic –enable-expires –enable-headers –enable-version –enable-ssl –enable-http –enable-cgi –enable-rewrite –enable-so –with-ssl=/usr/local/PACKAGES/openssl-0.9.8
make
make install

This will install Apache into /usr/local/PACKAGES/httpd-2.2.8.  If you want to make some modules shared (such as how we’re going to build mod_fastcgi shortly) then you can do so by adding things like: –enable-rewrite=shared.

The first part of installing fastcgi is to download fcgi from http://www.fastcgi.com.  To install this:

cd /usr/local/PKG_BUILD
tar -xvzf fcgi-2.4.0.tar.gz
cd fcgi-2.4.0
./configure –prefix=/usr/local/PACKAGES/fcgi-2.4.0
make
make install

The next step is to download mod_fastcgi (this is a DIFFERENT package to the fcgi one).  You can also download this from http://www.fastcgi.com/

cd /usr/local/PKG_BUILD
tar -xvzf mod_fastcgi-2.4.6.tar.gz
cd mod_fastcgi-2.4.6
cp Makefile.AP2 Makefile
make top_dir=/usr/local/PACKAGES/httpd-2.2.8/
make install top_dir=/usr/local/PACKAGES/httpd-2.2.8/

This will actually find your httpd source and compile mod_fastcgi for you, as well as install it with the Apache 2 modules! (Easy huh?).

The final step is to download and install PHP 5.  You can obtain PHP from http://www.php.net.  After downloading:

cd /usr/local/PKG_BUILD
tar -xvzf php-5.2.4.tar.gz
cd php-5.2.4

Now the next part will no doubt differ depending upon what features you want to compile PHP with.  That’s left up to you and google to work out how to compile the other modules.  I’ll show what we compile some of our systems with, but the only ones that are really applicable to this blog are the –enable-force-cgi-redirect –enable-fastcgi ones.

./configure  –prefix=/usr/local/PACKAGES/php-5.2.4-norm –with-openssl=/usr/local/PACKAGES/openssl-0.9.8d –with-zlib –enable-force-cgi-redirect –enable-fastcgi –with-mysql=/usr/local/PACKAGES/mysql-5.0.41 –enable-static –with-config-file-path=/etc/php.ini –with-imap –with-mcrypt –with-curl=/usr/local/PACKAGES/curl-7.16.1/ –with-kerberos –with-imap-ssl
make
make install

And that’s it for the compiling stage.  I’ll put up a blog at a later date on how to configure Apache 2 to work with FastCgi.  Stay tuned.