Should I back up all DynamoDB tables across all Regions

Question: I have a  AWS DynamoDB Global table spread across 2 regions . The usage is the application writes to Region 1 and replicates to the Region2. Should I back up all DynamoDB tables across all Regions ?

Answer: When you create a DynamoDB global table, it consists of multiple replica tables (one per Region) that DynamoDB treats as a single unit. But  the replicas created in the alternative Regions can also be backed up and restored individually. 

There are different ways of backing up DynamoDB - on-demand backups to both Service Native & AWS Backup , PointInTimeRecovery (PITR) but DynamoDB does not provide SLA for data durability - therefore backups are critical

With all these choices , there are number of  approaches and it will depend on the level of recoverability required and the purpose of the backup

Generally - For backing up DynamoDB global tables, a backup of DynamoDB tables in one Region should suffice and backing up all the replica tables in all Regions shouldn't be required. If the primary objective is to be able to recover user-error or corrupted  data, then PITR in one Region should be OK. Similarly, when preserving a snapshot for historic purposes such as regulatory requirements then backing up in one Region should suffice. The backed up data can be replicated to multiple Regions via the Backup Vaults replication mechanism in AWS Backup 

Ultimately - the answer depends on the data durability requirements ,purpose of the backup , compliance requirements and other specific RPO & RTO consideration