Web Hosting With Multiple Servers - Impact on a Website’s Uptime
By this article one can get to know about the technology used in multiple server hosting as well as how to utilize it to maximize one's site and security and uptime
Now the hosting of site has converted into a commodity where competition has raised to a very higher level and it's very difficult to discriminate among the hosting plans on the basis of core plans, features and prices. Moreover choosing a host based on the cheapest price is not a better idea rather it thereafter proves to be very expensive in terms of reliability as well as possible loss of sales as a result of website downtime.
Choosing a best out of thousands of providers and resellers is a very scary task, which is rather based on hit and trial method. Even if hosting has become a commodity still while choosing for new host one should look for reliability.
Now at the heart of any hosting company's reliability is redundancy. Redundancy offers an alternative remedy in case any problem occurs. This is to ensure continuity of work as seamlessly and transparently as possible.
There are several hosts, which employ redundant network connections. These are the high-speed pipes that route data from the server to one's web browser. As against this, redundant 'multiple web servers' are quite rare and expensive and so are rarely used. They are expensive due to use of costly routing equipment, which has previously been used, only in mission critical applications of Fortune 500 companies.
There is yet another very neat but little known Domain Name Server (DNS) feature called 'round robin' which allows the selection and provision of a particular IP address from a 'pool' of addresses when a DNS request arrives.
The Domain Name Server (DNS) database maps a host name to their IP address. Thus instead of remembering a vast series of numbers (IP address) one can just type in his/her web browser www.mydomain.com, to get to one's website.
Now in order to publicize DNS info throughout the market it will typically take minimum 2 to 3 days. That is the reason when one registers or transfer a domain name it isn't immediately available to the person browsing the web.
This delay has foiled the security benefits of hosting one's site on multiple servers, as the site would be down for a couple of days in case of any problem with one server. As a remedy one has to change his/her DNS to reflect the second server and has to wait for several days before the change was picked up in routers on the Internet.
There is yet another solution for the above problem i.e. the round robin DNS strategy that solves this quandary, by mapping one's domain name to more than one IP address.
One should now select that hosting companies which employs the DNS round robin technique in conjunction with'failover monitoring'.
The DNS round robin fail over monitoring process starts by a web hosting company setting up one's site on two or more independent web servers. Thus one's domain name will therefore have 2 or more IP Addresses assigned to it.
Thereafter the fail over monitor watches one's web server(s) by dispatching data to a URL one specifies and looks for particular text in the results. Now when an error is returned from one of an IP address, it pulls that IP address out of the list. The DNS thereafter points one's domain name to the working IP address/s
In case any of the user's IP's come back online they are restored to the IP pool. This helps in effectively and safely keeping one's site online even if one of the web servers is down.
In this case an average failure detection and recovery time with a system is very low with just 15 minutes. However this time varies depending on site's speed as well as the nature of the failure and also how long other ISP's cache (save) one's DNS information.
The time taken for other ISP's caching one's information can be manipulated in the fail over monitor by lowering the "time to live" (TTL) cache settings. These are the settings used by other ISP's in order to determine how long to cache one's DNS information.
One must also keep in mind the matter of how frequently data is synchronized between his/her website's servers. Now this comes under the hosting company's responsibility, and this becomes complicated where databases and user sessions are involved.
The most elegant solution to multi server hosting is very expensive hardware based fail over monitoring systems that point a virtual IP address to other ISP's, while behind the scenes juggling a number of unique IP addresses on different servers.
This way, the whole issue of ISP's caching one's information does not come into play.
Thus in order to get 99.99995% uptime, without spending big amount of money, the technology is readily available and certain proprietary failure monitoring systems are now relatively cheap to apply.
Now the hosting of site has converted into a commodity where competition has raised to a very higher level and it's very difficult to discriminate among the hosting plans on the basis of core plans, features and prices. Moreover choosing a host based on the cheapest price is not a better idea rather it thereafter proves to be very expensive in terms of reliability as well as possible loss of sales as a result of website downtime.
Choosing a best out of thousands of providers and resellers is a very scary task, which is rather based on hit and trial method. Even if hosting has become a commodity still while choosing for new host one should look for reliability.
Now at the heart of any hosting company's reliability is redundancy. Redundancy offers an alternative remedy in case any problem occurs. This is to ensure continuity of work as seamlessly and transparently as possible.
There are several hosts, which employ redundant network connections. These are the high-speed pipes that route data from the server to one's web browser. As against this, redundant 'multiple web servers' are quite rare and expensive and so are rarely used. They are expensive due to use of costly routing equipment, which has previously been used, only in mission critical applications of Fortune 500 companies.
There is yet another very neat but little known Domain Name Server (DNS) feature called 'round robin' which allows the selection and provision of a particular IP address from a 'pool' of addresses when a DNS request arrives.
The Domain Name Server (DNS) database maps a host name to their IP address. Thus instead of remembering a vast series of numbers (IP address) one can just type in his/her web browser www.mydomain.com, to get to one's website.
Now in order to publicize DNS info throughout the market it will typically take minimum 2 to 3 days. That is the reason when one registers or transfer a domain name it isn't immediately available to the person browsing the web.
This delay has foiled the security benefits of hosting one's site on multiple servers, as the site would be down for a couple of days in case of any problem with one server. As a remedy one has to change his/her DNS to reflect the second server and has to wait for several days before the change was picked up in routers on the Internet.
There is yet another solution for the above problem i.e. the round robin DNS strategy that solves this quandary, by mapping one's domain name to more than one IP address.
One should now select that hosting companies which employs the DNS round robin technique in conjunction with'failover monitoring'.
The DNS round robin fail over monitoring process starts by a web hosting company setting up one's site on two or more independent web servers. Thus one's domain name will therefore have 2 or more IP Addresses assigned to it.
Thereafter the fail over monitor watches one's web server(s) by dispatching data to a URL one specifies and looks for particular text in the results. Now when an error is returned from one of an IP address, it pulls that IP address out of the list. The DNS thereafter points one's domain name to the working IP address/s
In case any of the user's IP's come back online they are restored to the IP pool. This helps in effectively and safely keeping one's site online even if one of the web servers is down.
In this case an average failure detection and recovery time with a system is very low with just 15 minutes. However this time varies depending on site's speed as well as the nature of the failure and also how long other ISP's cache (save) one's DNS information.
The time taken for other ISP's caching one's information can be manipulated in the fail over monitor by lowering the "time to live" (TTL) cache settings. These are the settings used by other ISP's in order to determine how long to cache one's DNS information.
One must also keep in mind the matter of how frequently data is synchronized between his/her website's servers. Now this comes under the hosting company's responsibility, and this becomes complicated where databases and user sessions are involved.
The most elegant solution to multi server hosting is very expensive hardware based fail over monitoring systems that point a virtual IP address to other ISP's, while behind the scenes juggling a number of unique IP addresses on different servers.
This way, the whole issue of ISP's caching one's information does not come into play.
Thus in order to get 99.99995% uptime, without spending big amount of money, the technology is readily available and certain proprietary failure monitoring systems are now relatively cheap to apply.
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