FlashArray volume snapshots are a very fast way in which a consistent recovery point can be created for PostgreSQL clusters. it is possible for a PostgreSQL cluster to be deployed with a number of different Volume and File System Architectural Layout which will affect some aspects of the storage snapshot creation process.
Regardless of volume and file system architectural layout there are two methods of creating a PostgreSQL recovery point using storage snapshots:
- Application Consistent - An application consistent volume snapshot is typically performed by coordinating with the application and operating system to ensure everything is in a state that recovery is assured and possible to a point in time.
- Crash Consistent - A crash consistent volume snapshot ignores the presence or possibility of an application. No effort is made to ensure that the application is in a specific state and recovery to a point in time cannot be guaranteed.
Note:
It is not possible to backup isolated tables, databases or table spaces. In order for recovery to be possible the storage snapshot(s) must include all storage volumes in the PostgreSQL cluster.