2019.10.21 20:02:54.073200 [ 27 ] {2520c3a4-4105-40a1-8c35-cbf7494f310c} <Warning> StorageConfiguration: Volume `cold_hdd` max_data_part_size is too low (0.00 B < 8.00 MiB)

I would expect that when not provided (or provided as 0) = unlimited (i.e. any part size is allowed).