I get the message about using a pre-1.2.0 storage format. Is there a way to migrate? Are there any concerns on staying with 1.2.0 or benefits of switching?
Pre-1.2.0 storage uses zlib for compression and SHA256 for chunk hashes. New storage uses lz4 for compression and blake2 for chunk hashes. lz4 and blake2 are much faster than zlib and SHA256, and the backup speeds almost doubled in my tests.
My suggestion is to stay with 1.2.0 for now if performance is not critical to you, especially if you’re backing up to a cloud storage in which case the network is usually the bottleneck. Currently migration may not be possible due to a limitation of the copy command, but it should be fairly easy to make it work.