Can Opus verify file copies?

Can Directory Opus verify the data it writes when copying files?

Directory Opus does not currently have an option to verify file copies. We have investigated this in the past and our conclusion was that there's no real point in such a feature.

Firstly, the filesystem and storage hardware already has checksums and verifications built into it. If errors are detected writing to disk, this will normally result in an error code during the copy process.

But the main issue is that modern storage hardware almost always uses transparent RAM caches to increase performance. Data writes go into the cache in the first instance and then are lazily flushed to disk in the background. What this means is that if you read the data back after writing it, you're often simply reading back the cached data.

Data is unlikely to be corrupted during the copy process. It's more likely to happen sometime later (e.g. through hardware failure over time). In our opinion, if you're concerned about data integrity the only thing that really makes sense is to generate a hash of the files and periodically check that they still match that hash. (Or archiving them or backing them up with a backup tool, where you can test the archives/backups periodically.)

Directory Opus has a synchronisation tool which can be used to test if two folders are exactly the same (including comparing the contents of files), but using one of the free third party tools to generate/check hashes or PAR files would probably make more sense, and would mean they can be tested without the original data needing to be there. Using PAR files can also add some redundancy and lets you repair some errors if they occur later on.

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