AWS Storage, storage

How AWS snapshot works? Is Incremental?



How AWS snapshot works? Is Incremental?

*Normally when you take backup of Amazon EC2 EBS volume, backup  will be stored in S3 called “Snapshot”

*AWS users will not have any visibility on backend process.These backup are not visible as S3 bucket formats eventhough its stored   in S3. You can only view snapshot details in console

*You can back up the data on your Amazon EBS volumes to Amazon S3 by taking point-in-time snapshots.

*Snapshots are incremental backups, which means that only the blocks on the device that have changed after your most recent snapshot are saved. This minimizes the time required to create the snapshot and saves on storage costs by not duplicating data.

*When you delete a snapshot, only the data unique to that snapshot is removed. Each snapshot contains all of the information needed to restore your data (from the moment when the snapshot was taken) to a new EBS volume.


                           How Incremental concepts works in AWS

Source : AWS Documentation – EBS snapshot.

In the diagram above, Volume 1 is shown at three points in time. A snapshot is taken of each of these three volume states.

*In State 1, the volume has 10 GiB of data. Because Snap A is the first snapshot taken of the volume, the entire 10 GiB of data must be copied.

*In State 2, the volume still contains 10 GiB of data, but 4 GiB have changed. Snap B needs to copy and store only the 4 GiB that changed after Snap A was taken. The other 6 GiB of unchanged data, which are already copied and stored in Snap A, are referenced by Snap B rather than (again) copied. This is indicated by the dashed arrow.

*In State 3, 2 GiB of data have been added to the volume, for a total of 12 GiB. Snap C needs to copy the 2 GiB that were added after Snap B was taken. As shown by the dashed arrows, Snap C also references the 4 GiB of data stored in Snap B, and the 6 GiB of data stored in Snap A. The total storage required for the three snapshots is 16 GiB.



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