The following describes the format of a single chunks file, which is created in the `chunks/` directory of a block. The maximum size per segment file is 512MiB.
Chunks in the files are referenced from the index by the in-file offset in the 4 LSB and the segment sequence number in the higher 4 MSBs.
Chunks in the files are referenced from the index by uint64 composed of in-file offset (lower 4 bytes) and segment sequence number (upper 4 bytes).