Do you have one?
Backups are often done incorrectly, inaccurately or not at all. What should we do when planning our backup? Having no backup strategy is almost as bad as having no backups. Our backup strategy tells us a few things:
When to backup. (not how many times a day or week, but WHEN).
Running backups on load critical servers when the load is at a peak is not a good idea. Certain backup types (is Databases) need a microsecond pause to create an accurate snapshot. Other backup technologies may freeze a server for a few seconds. Either way – the load handling ability of your equipment WILL be affected. Plan your backups to start after PEAK and complete before the next load demand. This is usually in the evenings, say from 19:00 up to 06:00.
How often to backup.
Making 2 copies a day of data that changes once a week is a waste of time and resources. Making one copy a month of data that gets updated daily is highly negligent. Plan your backup FREQUENCY to match your data update periods as closely as is feasible. All backups must allow for a certain amount of “Acceptable” loss – the amount of data between your last backup and the dreaded “CRASH”. This is reckoned in the worst case as the interval between backups. Making use of incremental backups can give you more backups for less space. File-based backups give you more flexibility than disk or system images as they usually run a lot faster and are easier to do incrementally.
What to backup.
This is not a trick question. Making a backup of readily available software or standard operating system files is not needed and wastes space and resources. Including these in a monthly image backup for ease of restoration is fine. Including them in a daily backup is just stupid. This brings us to our fourth point…
Differentiate your backups.
Make a monthly or bimonthly archival image backup and do the rest as file backups with a weekly full and daily incremental backups. This ensures that your backups are both complete and fast.
Ensure that your backup strategy is fully approved by management and follows your DR (Disaster Recovery) Plan. Document your backups and make sure you know where they are. Also, make sure that any legal compliance is addressed and that management knows the extent of backups. If you do not, you may have a very upset CEO who cannot recover that critical email with the contracts attached which he received 6 years ago because your backup compliance only asks for a 5-year retention. With the above scenario in mind, keep archival copies for at least 10 years of you can – make an archive every 6 months and it does not take that much space (relative to your total backup space).