Suspect below. You can drop it back to 0 if you like, but that’s 1 sample for big backup:
2.0.8.1 help text:
--backup-test-percentage (Integer): The percentage of samples to test after
a backup
After a backup is completed, some (dblock, dindex, dlist) files from the
remote backend are selected for verification. Use this option to specify
the percentage (between 0 and 100) of files to test. If the
backup-test-samples option is also provided, the number of samples tested
is the maximum implied by the two options. If the no-backend-verification
option is provided, no remote files are verified.
* default value: 0
2.1.0.2 help text:
--backup-test-percentage (Decimal): The percentage of samples to test after a backup
After a backup is completed, some (dblock, dindex, dlist) files from the remote backend are selected for verification. Use this option to specify the percentage (between 0 and 100) of files to test. If
the option --backup-test-samples is also provided, the number of samples tested is the maximum implied by the two options. If the option --no-backend-verification is provided, no remote files are
verified.
* default value: 0.1
There is also --backup-test-samples, if you prefer an absolute number over percentage.
I don’t know if there’s any “right” setting – it depends on how carefully you want to check…
Backup Test block selection logic is what used to be (likely still is) how the sampling is set.
Possibly it could be tweaked someday, e.g. to avoid repeat sampling for any who are sure destination will never bit-rot a file once it’s there, but are less sure about correct uploading.