ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel
  • »
  • Technology»
  • Internet & the Web

What is Redundancy?

Updated on October 7, 2015
Source

Colocation & Redundancy

In previous articles I have looked at various aspects of data centres, how environmentally friendly they are and the features that they often have. When learning about data centres, an important concept to understand is ‘redundancy’. Although the term can be used to describe a form of dismissal from a job, in more technical circles it is a useful concept that can help to provide back-ups and extra security in the event of equipment failure or a power cut. You will often find various forms of redundancy being used in colocation centres.

Colocation is a form of web hosting where space in a data centre is rented out to businesses and individuals. Instead of all the servers and equipment in the centre belonging to one company, in a colocation centre the servers of different businesses and customers are housed. You can often also rent a server if you do not have one of your own and can choose a managed hosting plan, where the data centre looks after the maintenance and upkeep of the server for you. The data centre will also provide the bandwidth and the power for the servers. The main aim of any data centre is to achieve high levels of uptime and to make sure that customers’ systems are available at all times. This is where the concept of redundancy is useful.

Source

The Concept of Redundancy

In basic terms, redundancy is where important aspects of the system are duplicated. Through doing this with their equipment data centres can vastly improve their uptime and the reliability of their whole operation. With redundancy measures in place, if a piece of equipment fails or needs replacing, then another component can immediately take its place and the system remains up and running. Without redundancy, if a component breaks it could bring down the whole network and important data could be lost. Colocation centres will often implement ‘N+1 redundancy’ (or ‘parallel redundancy’), this is where any piece of equipment or component has one additional unit and the resource is shared between them. For example, if you have one server - you should add an additional server and they should both be running at 50% power or capacity. This means that if one server fails, the other server can immediately take over and will not overload. The process scales up, so if you have two servers, you should add an additional server and the three units should be running at 66% capacity.

Source

An Engineering Example

Redundancy is a concept that is also found in engineering and building works as well as in the data centre. Suspension bridges are a particularly good example of redundancy in action. Suspension bridges are held up by a large amount of cables - often made of metal - where the weight is distributed evenly between them. The weight that each cable is supporting is not the maximum amount of weight that it can hold, i.e. each cable has the capacity to support more weight. This means that if a cable should break or is cut the remaining cables would be able to support the extra weight and the bridge would not collapse. Redundancy in data centres does not need to utilise as many additional units as there are cables in a suspension bridge, but it is advised that the capacity or power of a unit should be spread between three separate units as this will vastly improve reliability.

Source

Power Supply

The main problems that redundancy helps to guard against are power failures and power surges. If there is a power failure it can bring the whole centre to a halt and can result in the loss of customers’ data or making their website unavailable. Equally a power cut or a power surge can stop the air conditioning and cooling systems from functioning and could lead the servers, which need to be kept at precise temperatures, to overheat and crash. In order to avoid the problems caused by power cuts and surges, redundancy can be implemented. Most colocation centres will receive their power from at least two separate power supplies, often more. If there is a power cut at one of the power supply stations, the others can easily make sure that the data centre continues to receive enough power to run. In the highly rare case that all external power supplies fail, most centres will have a backup in the form of an ‘uninterruptible power supply’ or ‘UPS’ that can temporarily power the centre until the supply comes back on. Backup power options such as UPSs and generators will utilise N+1 redundancy, so that if the backup fails, there is a backup for the backup!

Source

Internet Connection

Another area that redundancy can be used is for the internet connection as it is highly crucial that data centres stay connected to the internet at all times. The vast majority of colocation and data centres will utilise several telecoms providers and will have the centre connected via several different fibre optic cables. This means that if the connection is lost from one provider or one cable, it will not affect the whole centre. Connecting to the internet through both a wired connection and wirelessly is another important form of redundancy. Applying redundancy to the internet connection can help data centres to achieve high levels of latency and can ensure that connectivity is maintained almost 100% of the time.

Air Cooling & Conditioning

The final way that redundancy is used in data centres is in the temperature control and air conditioning systems. As data centres are constantly running large numbers of machines, the temperature can quickly rise and servers, which need to be kept at precise temperatures, can easily overheat. So, much like the internet connection and the power supply, the cooling and temperature regulation system needs to be kept online 24/7. The Computer Room Air Conditioner units, or CRACs, will utilise N+1 redundancy so that the centre will stay cool, even if a CRAC malfunctions. N+1 redundancy will also be applied to the pipes that are connected to the CRACs and the ‘chillers’ that support the CRACs. Redundancy, therefore, is a hugely important concept in any form of data centre. Most centres will advertise their high levels of uptime, the way they are able to follow through on their claims is through using redundancy.

Comments & Questions

Submit a Comment

No comments yet.

working

This website uses cookies

As a user in the EEA, your approval is needed on a few things. To provide a better website experience, hubpages.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: "https://hubpages.com/privacy-policy#gdpr"

Show Details
Necessary
HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
LoginThis is necessary to sign in to the HubPages Service.
Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
AkismetThis is used to detect comment spam. (Privacy Policy)
HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
Amazon Web ServicesThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized. (Privacy Policy)
CloudflareThis is used to quickly and efficiently deliver files such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
Features
Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
MavenThis supports the Maven widget and search functionality. (Privacy Policy)
Marketing
Google AdSenseThis is an ad network. (Privacy Policy)
Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
Index ExchangeThis is an ad network. (Privacy Policy)
SovrnThis is an ad network. (Privacy Policy)
Facebook AdsThis is an ad network. (Privacy Policy)
Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
AppNexusThis is an ad network. (Privacy Policy)
OpenxThis is an ad network. (Privacy Policy)
Rubicon ProjectThis is an ad network. (Privacy Policy)
TripleLiftThis is an ad network. (Privacy Policy)
Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisements has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
Statistics
Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)