January 6, 2014

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Every admin should have a backup. This principle works for any virtual environment; regardless of the hypervisor you are running (VMware, Hyper-V or whatever): backup is king!

One of the timeless rules that can effectively address any failure scenario is called the 3-2-1 backup rule. This approach helps to answer two important questions: how many backup files should I have and where should I store them?

The 3-2-1 rule became a popular concept thanks to Peter Krogh, a well-known photographer who wrote that there are two groups of people: those who have already had a storage failure and those who will have one in the future. In other words, the 3-2-1 backup rule means you should:

  • Have at least three copies of your data.
  • Store the copies on two different media.
  • Keep one backup copy offsite.

Let’s consider these statements one by one in more details.

1. Have at least three copies of data

By three copies, I mean that in addition to your primary data, you should also have at least two more backups. Why isn’t one backup enough? Imagine that you keep your original data on device #1 and its backup is on device #2. Both devices have the same characteristics, and their failures are statistically independent (they have no common failure causes). For example, if device #1 has a probability of failure that’s 1/100 (and the same is true for device #2), then the probability of failure of both devices at the same time is:

1/100 * 1/100 = 1/10,000

 

This means that if you have your primary data (on device #1) and two backups of it (on devices #2 and #3, correspondingly), and if all devices have the same characteristics and no common failure causes, then the probability of failure of all three devices at the same time will be:

1/100 * 1/100 * 1/100 = 1/1,000,000

 

This is why having more copies of your data means you will have less risk of losing data during a disaster. In short, if your data is important to you, be sure to make at least two backup copies.

Note: Another reason to create more than two copies of data is to avoid the situation when the primary copy and its backup are stored in the same physical location.

2. Store the copies on two different media

In the section above, we assumed that there were no common failure causes for all of the devices where you store your data copies. Obviously, this requirement cannot be fulfilled if you save your primary data and its backup in the same place. (For example, disks from the same RAID aren’t statistically independent.) Moreover, it is not uncommon after one disk failure, to experience failure of another disk from the same storage around the same time.

That’s why the 3-2-1 rule suggests that you keep copies of your data on at least two different storage types, such as internal hard disk drives AND removable storage media (tapes, external hard drives, USB drives, SD-cards, CDs, DVDs, or even floppy disks), or on two internal hard disk drives in different storage locations.

3. Keep one backup copy offsite

Physical separation between copies is important. It’s really not a good idea to keep your external storage device in the same room as your production storage. If there was a fire (knock on wood!), you would lose all of your data.

If you work for a company that’s an SMB with no remote or branch offices (ROBO), storing your backups to the cloud might also be an option. And tapes taken offsite are still popular among all company sizes.

 

The 3-2-1-0 backup rule

The 3-2-1 rule is very general and it works for all data types (individual and corporate) and all environment types (physical and virtual).

When backing up VMware or Hyper-V environments with Veeam, this rule becomes the “3-2-1-0 backup rule” where 0 means “0 errors” during the automatic recoverability verification of every backup with Veeam’s SureBackup.

 

Veeam Backup & Replication™ can help you to fulfil all 3-2-1 backup rule requirements.

  • Have at least three copies of data: Setup Backup Jobs to create several backups for each of your VMware or Hyper-V VMs.
  • Store the copies on two different media: Veeam is storage-agnostic, meaning it supports tapes, disks, the cloud and more. You can store your backups to any of the listed media.
  • Keep one backup copy offsite: Setup Backup Copy Jobs to transfer your backup offsite faster with built-in WAN acceleration, or use Veeam Backup Cloud Edition to store your backups to one of 15 public clouds, including Windows Azure, Amazon Glacier, Google Cloud Storage and more.

Do you apply the 3-2-1 backup rule in your environment? As always, you can comment below or reach me on Google+ or Spiceworks.

 

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