Snapshot AWS EBS

EBS Snapshot
EBS allows you to create snapshots (backups), and then write a copy to S3. The volume’s data is redundantly stored in multiple Availability Zones.
Snapshots can also be used to create new volumes or increase the volume of existing volumes.
Snapshots are incremental backups that store only the data that has changed since the last snapshot was taken.
Snapshots can be smaller than volume because the data is compressed before being saved as S3
Although snapshots are saved incrementally over time, the snapshot deletion process requires that you only retain the most recent snapshot to restore the volume.
Multi-Volume Snapshots
Snapshots can be used for backups of critical workloads such as large databases or file systems that span multiple EBS volumes.
Multi-volume snapshots allow you to take precise point-in-time, crash-consistent snapshots of multiple EBS volumes attached at an EC2 instance.
EBS Snapshot creation
Snapshots can also be created periodically from EBS volumes and are point-in time snapshots.
Snapshots are incremental. They only store the blocks that have changed since the last snapshot was taken.
Snapshots are created asynchronously. The snapshot is created instantly while the modified blocks are uploaded to S3. While the snapshot is being completed, it is not affected by ongoing reads or writes to the volume.
Snapshots can also be taken from volumes that are not in use. Snapshots can only capture data that was written to EBS volumes at the time of the snapshot command is issued. This excludes data that is cached by OS applications.
The best way to create a Snapshot using an EBS volume is to stop all file writes to it
Take a Snapshot -> Unmount the Volume
Stop the instance – Take Snapshot
EBS volume created from a snapshotbegins is an exact replica the original volume that was used for the snapshot.
Data from replicated volume loads can be stored in the background, so it can be used immediately.
If data is not loaded yet, the volume downloads the requested data immediately from S3 and then continues loading all the data in the background. EBS Snapshot Deletion
Only the snapshot data is deleted when a snapshot is deleted.
The ability to restore volumes from earlier snapshots of a volume is not affected by the deletion of previous snapshots.
Active snapshots contain all the information required to restore your data (from when the snapshot was taken) and to create a new EBS volume.
Although snapshots are saved incrementally over time, the snapshot deletion process requires that you only retain the most recent snapshot to restore the volume.
Snapshot of root device of EBS volume used to register AMI cannot be deleted. To delete the snapshot, AMI must be deregistered.
Snapshots are limited to the region where they were created. They can only be used to launch EBS volumes in the same region.
Snapshots can also be copied across regions, making it easier to use multiple regions for geographic expansion, data center migration and disaster recovery.
Snapshots are copied using S3 server-side encryption (256 bit Advanced Encryption standard) to encrypt data. The snapshot copy also receives an ID that is different from the original snapshot’s ID.
User-definable tags are not copied from the source to a new snapshot.
The first Snapshot copy to another area is always a complete copy, while the rest are a summary.