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–backup-test-percentage is a scaled-with-backup-size version of –backup-test-samples, which is a semi-random sample with more attention paid to less sampled items. Backup Test block selection logic details.
Add backup-test-percentage in addition to backup-test-samples [$25] #3296 is the feature request for this.
If you’re asking for verification of uploaded files, you might try list-verify-uploads (which seems little used). This looks like it should at least check file existence and size. It won’t actually download file to check data. There’s always (unless you turn it off) a check of all uploaded files (even old ones) list at end of backup.
If original data refers to source files, that’s a step farther removed, and that type of test also doesn’t exist, though there’s probably a feature request somewhere… For now, manual restore tests are the way to go.
Restore checks the file hash of the restored file against the original database record, so “should” be good even if you no longer have that particular version (or any version) of the source file in the original location.
Is RAID the source file system that’s being backed up with Duplicati as well as file-copied to slower HDD? That shouldn’t have any impact on verification except that any problem found may mean going to the copy.
I recommend against using Duplicati as a “backup-then-delete” archive, but a second copy makes it safer.
What is Duplicati backing up to? If it’s accessible locally, –upload-verification-file will let you verify data with one of the DuplicatiVerify.* scripts in the Duplicati utilities directory, but it will be read-everything verification.