Does Duplicacy ensure the integrity of restored files?

What happens if a bit get flipped in a chunk file? Does the restore fail when it gets to restoring that chunk?
Therefore, can you be sure that all the bits are correct in the restored files if the restore completes?

If there is a bit flip in a chunk you won’t even be able to download the chunk since the chunk hash will be different.

On top of that, after a file is restored its hash is compared with the known hash stored in the backup. The restore will fail if two hashes are different.

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As @gchen explained, Duplicacy depends on the file system to provide long-term reliable storage. In practice that means that cheap onsite storage like external HDDs is not suitable as backup storage medium for any important data.

You need a file system like ZFS or BTRFS that has built-in checksums to detect bit rot and you need disk redundancy through RAID, so these file systems are able to repair detected checksum errors by reading the data from the redundant media.

For most non-business users with (presumably) a limited amount of important data using an off-site backup might be cheaper than a suitable onsite solution, say a NAS in the appropriate configuration.

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Good answers. Thanks.