Simon Miller Team : Web Development Tags : Web Development Performance Featured

Disaster Recovery and Redundancy for Websites

Simon Miller Team : Web Development Tags : Web Development Performance Featured

How important is DR for you?

The answer to this question should be simple: paramount. When a business is spending a substantial amount of money on a website to be designed and developed, so should they also be investing in a solid Disaster Recovery plan. There have been significant cases when a disaster has occurred to a website where so much data was lost that the impact on a business was catastrophic.

Most websites are generally not of the size that require over-the-top DR plans that a financial institution or government department may require. With more and more websites now being hosted in virtual environments, it is assumed by most that the web host undertake DR preparations independently of your own website; your site is most likely just a virtual image on a large array of drives, protected by all kinds of hardware and software failover precautions offered to multiple customers concurrently. However ignorance in this case is not bliss – take ownership of your DR plans: know what you are getting, and understand how to make use of it.


The importance of a good backup regime

A backup is only as good as the ability to restore it.

You need to be sure you can test the backup and restore procedure offered by your host and be confident in the results. Ask how you can go about testing the backup procedure – perhaps they can spin up a temporary site for you to test. Plan ahead, know your contact points and know the agreement you have with your host should you require immediate recovery of a backup.

You do not want to be in a position where bad communication has resulted in no or infrequent backups, or no easy access to having backups restored. Without question you will require daily backups of your site data, though the frequency of incremental backups (hourly or less) is up to your discretion and budget (the higher the better).


Redundant redundancy

With the above in mind, it is still possible for irrecoverable data loss to occur and your web host being unable to assist. It is therefore highly recommended that you conduct your own backups in addition to what your host offers.

For a smaller scale site this may simply mean routinely zipping up the website files and exporting the database to your local environment.

High frequency is unrealistic for such a task but once per week would guarantee you always have a fairly recent copy of your site in which to fall back to should all other options fail. You should also determine your host’s policy in such situations.

For larger scale websites that have physical hardware in place, you may be able to organise personal backups to data tape or external hard drives that can be collected and taken off-site should the ultimate disaster occur (such as damage to your hosting environment caused by flood or fire).


How much downtime can you absorb?

Secondarily to this article but of related concern is knowing how outages will affect your website. No hosting provider will offer 100% uptime, but many will offer 99.9% uptime. You need to understand what this means and what is not covered in that 0.1%. Larger hosts will have battery-backup for their services; even larger will have fuel backups for the batteries, or duplicates of the entire environment in another location on another power grid and Internet backbone.

The greater your requirement, undoubtedly the greater the cost, so choose the most appropriate options for the size of your website and budget. If money is no object, you could consider having a duplicate of your site running with an entirely separate provider – this is extreme and failover would not be automatic, but is definitely an option you could consider if you are aiming for 100% uptime.