Deduplication and redundancy questions

hey everybody.

1. Deduplication
"When given a list of files it will hash their contents on a block by block basis" - are those static blocks or is the length of a block defined by its content? (that would be more resilient regarding inserts of data and the shift of the following data caused by it)

Do I understand correctly, that I better use bedup to deduplicate on a file-level before using duperomve to deduplicate on a block-level?

2. Redundany
"Background scrub process for finding and fixing errors on files with redundant copies " So fixing is only available with full redundancy?! No parity-based methods or other ECC-based approaches?!

thanks for answers

"Block" generally refers to a 4 KiB piece of data. In btrfs,
contiguous blocks form extents, and a file may be made up of none or more extents stored in different places on the disk.

If you really do block-level dedup, then that would make little
sense to do file-level dedup afterwards. As I understand it, duperemove actually works on an extent level, rather than a block level. (Note that block-level deduplication is likely to lead to truly appalling performance, due to large amounts of seeking).

Correct. The checksums used for this are (currently) 32 bits for
each 4 KiB block. There's simply not enough information there to do anything other than detect (most) errors. If you want parity-based repair of errors, use RAID-5 storage.

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