3-2-1 Backups

May 19, 2010

When it comes to backups, there is a general rule that should be kept in mind. It is known as the “3-2-1” rule. It means there should always be 3 copies of all critical information on 2 different storage mediums 1 of which is offsite. By following this strategy you know that if a problem arises you will be prepared and your data will be secure.

It is important to have multiple copies of your data. When discussing the 3-2-1 backup strategy, the first set is the original data: this is the information you work with in real time. The second and third sets of data are considered backups of the original information, but the backups are of 2 different types. Backups
For the two backup copies, they need to be on two different mediums. This is a measure taken for security reasons, in case something happens to one copy, or if something is somehow damaged. Having two copies on two different mediums is essential for a good backup strategy. Some of the most commonly used mediums for backups: external hard drive / USB drive, CD/DVD, tapes, online backup. There are different benefits for each backup medium. For example, tapes are easy to take offsite, but you have to have a tape-reader in order to use them, and tapes have to be regularly changed. Servers may have tape drives built into them, so using backup tapes makes sense in that case. CDs and DVDs are also easy to take off site, but they don’t hold as much data as tapes or external hard drives and also require user intervention. External hard drives are large and easy to transport, but they are also fragile and sensitive to damage. Online backups can be done automatically, and you don’t have to worry about physically changing a tape or taking the backup off site, because it is all done for you, but you do have to worry about bandwidth.

Following the 3-2-1 procedure means that one of the backups should be offsite. There are many reasons for this. First off, if you have all of your data backed up on tapes or an external hard drive that are left on site and there is a burglary, fire, or other natural disaster, then there is a good chance that your backup will be damaged or destroyed. Just because one of the backups needs to be off site does not mean it has to be online. If you are using tape backups or an external hard drive and you take it off site every night then that is considered an off site backup. The reason that Emerson Technologies recommends online backups is because they are very easy to configure, they run automatically, and they are already offsite. This means somebody doesn’t have to remember to take something home every night and every morning.

Here are some examples of recommended 3-2-1 backup strategies:

Strategy 1: External hard drive and online backups – Recommended by Emerson Technologies
3 copies of data – One live copy, one copy on an external hard drive, one copy backed up online.
2 different backup mediums – External hard drive and online
1 offsite backup – Online

Strategy 2: Backup tapes and online backups
3 copies of data – One live copy, one copy on backup tapes, one copy backed up online.
2 different backup mediums – Tapes and online
1 offsite backup – Online

Strategy 3: External hard drive and backup tapes
3 copies of data – One live copy, one copy on an external hard drive, one copy on backup tapes.
2 different backup mediums – External hard drive and tapes.
1 offsite backup – Either take tapes home every night, or take external hard drive home.
If you have any questions about your backup strategy, or if you would like Emerson Technologies to help you in any way, please give us a call at 651-454-7729 and we would be happy to help.


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