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Backing up

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Posted 30-01-2009 at 07:25 PM by Paul

While most shared web hosting providers understand the need for regular backups there are many ways to do these backups and these different methods give different levels of protection from data loss. Therefore it is important as a hosting client that you have a basic understanding so that you can ensure that the backup strategy offered by the host satisfies your requirements. The following details some of these backup strategies.

Backing up to a secondary drive in the server

It is quite common for a server to be fitted with a secondary hard drive, cPanel can then be told to make backups to this drive with a daily, weekly and monthly rotation.

However:
  • If the server fails then there is no access to the live data or the backups.
  • If a hacker compromises the server then they can tamper with both the live data and backups.
  • If a software or hardware fault occurs that corrupts the disks then as both the live data and backups are on the same machine there is a chance all will be lost.

Single shot backups

Another common approach is to take weekly backups and store them off server but only the latest copy of the backups is kept, that is as the new backups are written the previous ones are overwritten. While backups are now off server and more protected there are still problems:
  • If a server is hacked just before the backups run then hacked data could be backed up rendering the backups useless.
  • If the backups fail and result in corrupt backups there’s only the live data available.
  • There’s no history kept so once the backups have run a file deleted 2 days ago can’t be retrieved.

Backing up off server but on site

Data is backed up, preferably with history, and stored off server but within the data centre. Should the server be lost data can be recovered from the backup storage. However should all access to the data centre be lost so will access to both the live and backup data.

Backing up off site

This is potentially the safest option.

Usually backups are made, again with history, to an on site backup area as this gives the best restore performance, then periodically a copy of the backup data is moved to an off site location.

Should any disaster befall the data centre then data, all be it slightly older data, can be recovered from the off site location allowing a business to continue with minimal loss.

RAID as backup

There sometimes seems to be confusion as to what RAID is, RAID is not a backup solution it is intended to improve uptime of the server, RAID is no defence against accidental deletion of files or file system corruption.

For example RAID 1 uses two disks with identical copies of data on each, if either disk fails the server can continue running by using the still serviceable drive. However as each disk holds an identical copy of the data deleting a file will delete it from both drives.

RAID should be used to improve the resilience of servers but a proper backup system must still be employed.

Finally

You should select a host that provides a backup strategy suitable for your needs. If the data is important to your business then you should be taking periodic backups of your files and databases and storing these safely at your office or other suitable location. If there’s any doubt as to the importance of your data then you should ask yourself the question what would happen to my business if I lost all the data in my hosting account?
Posted in Web Hosting
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