What does it mean, and how does it affect your backups?
The simple definition of immutable is "unchanging over time or cannot be changed". If we apply this to a backup, we are now talking immutable backups. Backed-up data needs to be stored on immutable media, so that it cannot be changed.
So, you might ask: Why would I be concerned about this? Our Datto backups are stored in two places: on the Datto appliance and in the cloud. This data should be safe, and it should be accessible as needed for a restore. The bigger concern, really, is ransomware. The nefarious bad people in the world of ransomware are now able to insert their ransomware into the backups of your data. If your backed-up data is not stored on immutable media, it is susceptible to ransomware attacks.
If you are attacked by ransomware, backups are the de facto way to recover from this. If your backups are also attacked, then your data is at serious risk of not being able to be restored.
NOT ALL BACKUP MEDIA OR BACKUP SOLUTIONS ARE IMMUTABLE.
Tape media is immutable and may be the single best place for your backed-up data. It can be stored for years (in proper conditions); however, it also requires a lot of maintenance. Moving tapes in and out of the tape library and to offsite storage, purchasing new tapes, replacing old tapes, and removing tapes out of long-term storage when a company's data retention policies require archived data to be purged. Depending on the amount of data a company has, this could involve hundreds of tapes, and certainly a lot of man hours to maintain.
Digital media is much easier to use but is more susceptible to ransomware. One reason for this susceptibility is that digital media is on the network. During a ransomware attack, any information on the network being attacked is vulnerable. Most backups today are solutions using digital media.
As you review backup solutions for your company, make sure that the backup vendor is using immutable technology. This is usually in the form of signed APIs that allow only the backup software to write to the media.
Another note to take into consideration when reviewing backup options and how immutability may be a factor: what type of business are you in and are there compliancy governance that require immutable technology?
Datto backups are immutable. Additionally, Datto has implemented several security updates in recent years, making access to the Datto backup environment more secure. This Datto blog article goes into more depth on their backup solution, and I invite you to read it for more detail.