I think generally speaking, databases are resilient to this so taking a snapshot of the disk at any point is sufficient as a backup. The only danger is if you're using some sort of on-controller disk cache with no battery backup, then basically you're lying to the database about what has flushed and there can be inconsistencies on "power failure" (i.e. live snapshot).
But for the most part as especially in the cloud, this shouldn't be an issue.
Beware that although databases are resilient to snapshotting, they're not resilient to inconsistent snapshots. All files have to be snapshotted at the exact same moment, which means either a filesystem-level or disk-level snapshot, or SIGSTOP all database processes before doing your recursive copy or rsync.
Some databases have the ability to stop writing and hold all changes in memory (or only append to WAL, which is recursive-copy-safe) while you tell it you're doing a backup.
But for the most part as especially in the cloud, this shouldn't be an issue.