As a more cost effective way of providing redundancy, in the case of a third party or customer hosted website, we can host a backup copy of your website on our servers. In the event of failure traffic to your site can then be diverted to our servers while the issue causing the problem can be resolved. This can be a very cost effective way of ensuring your website doesn't suffer unnecessary down time and disruption for your visitors.
Dual hosting your website on a third party server, or even your own server, and then having a backup site on our servers is fairly straightforward to set up. In the event of failure a visitor trying to connect to your website is automatically diverted to the backup site quite seamlessly through DNS failover. DNS, which stands for Dynamic Name System, is in essence the index for the Internet. When an address such as www.designerwebapplications.co.uk is requested a visitor's computer makes an enquiry to DNS for the IP address of the hosting server. Your computer then use this IP address from then on. Through one of our providers we can configure DNS to automatically give the address of either the main production server or our backup server depending on the response of certain preset criteria. To facilitate this a complete copy of your website sits dormant on our servers. Backup copies of your database are regularly transferred to our servers, and when required are brought on line. Your visitors then use the backup copy of your site without noticing the swap over.
The process described above is pretty much an industry standard disaster recovery method. The frequency of backup copies of your database being copied to our servers decides how "in sync" the reserve copy of your website is with the main production site. In reality this is usually based on the latest full database backup, however differential backups of the changes since the last full backup can also be transferred. Consequently this could provide a solution that is little more than an hour or so behind the live system. If the main production server fails over night this would probably mean the environments were completely up to date. If it's the middle of the business day or during a busier time then you might lose an hour's worth of data during the down period.
The DNS failover described above although automatic isn't instant as it has to "detect" the failure. Once detected it will switch over instantly, however the very nature of DNS means that a computer may not pick up the change for a few minutes. Ultimately though within under five minutes your website should be being served from our backup servers.