February 16, 2016
How Datto’s Inverse Chain Technology Works
Datto’s Inverse Chain Technology is an efficient and resilient alternative to traditional incremental backup. It is designed to offer the fastest possible restore times while keeping capacity demands in check.
Incremental backup has operated on the same basic principle since tape was the preferred target. First, a full backup is created. Then, subsequent backups only copy data that has changed since that initial full. These incremental backups are quick and require little compute resources, because you aren’t copying a whole lot of data. But, when it comes to restores… it’s complicated.
In order to recover data, the backup system must rebuild a full backup from a chain of incrementals. So, the rebuild process can be slow, but that’s only part of the problem. What’s worse is that the full backup and every subsequent incremental have a dependent relationship. So, if one incremental is corrupt, all of the recovery points that follow become unusable. And, there is no way to delete older incrementals; the only option is to consolidate them and start the madness all over again.
Datto’s Inverse Chain Technology takes all of that and turns it on its ear. Each time a snapshot-based incremental backup is taken, changes are replicated on the Datto device (and to Datto’s cloud) creating a perfectly mirrored copy of protected servers. Instead of chains of dependent incrementals, Inverse Chain Technology stores every previous recovery point in an independent, fully constructed state, so there is no rebuild process when reverting to a previous point in time.
Wait, what? Backups on backups on backups? Doesn’t that require tons of capacity?
Nope, and here’s why: Inverse Chain Technology uses ZFS’s “copy on write” capability, so each unique block of data is saved only once and is referenced by all of the restore points that use it. Also, since each point is completely independent you can delete older recovery points that are no longer necessary—further reducing capacity demands.
Why you should care
In the event of an outage on a primary server, Inverse Chain Technology allows you to spin up virtual machines on the Datto device or in Datto’s cloud very quickly, dramatically reducing RTO. It also allows you to create backups as often as every five minutes for low RPO. And it reduces the amount of management associated with traditional incremental backup. Frequent pruning and regular full backups are no longer required to prevent the backup system from reaching full capacity. You can delete recovery points without ever having to reset the backup chain, and different sets of recovery points on the Datto device and in Datto cloud. Inverse Chain Technology is a native feature of Datto’s SIRIS 2, Virtual SIRIS, ALTO 2, ALTO XL and Virtual ALTO systems.