Reasonable thought, maybe tripped up by implementation details. A fully filled block could certainly be large.
The key word there might be could. File chunks are sometimes small, and if a small block gets in the dblock, my theory is your dblock felt full either then or when a block of full dblock size arrived. A file also has a small block of metadata which on Windows is mainly file times. From the ending of How the backup process works:
Many details were omitted from the above example run, some of those details can be summarized as:
* Metadata is treated like a normal block of data
* When a `dblock` size is too big, a new one is created
I tried testing my theory before posting it by using --dblock-size=500MB with --blocksize=100MB, hoping that dblock files would be written partly filled, but not as almost-empty as yours, and that seemed to be the case:
11/28/2018 02:47 PM 1,617,661 duplicati-20181128T191256Z.dlist.zip.aes
11/28/2018 02:14 PM 433,512,925 duplicati-b0dea11c17768423f8a7f0318f0c039c7.dblock.zip.aes
11/28/2018 02:17 PM 514,909,101 duplicati-b18abd26beee649edb84c3fffd852399b.dblock.zip.aes
11/28/2018 02:24 PM 462,481,805 duplicati-b3a67e0f277e84ee7819757761a07cdbb.dblock.zip.aes
11/28/2018 02:14 PM 424,773,229 duplicati-b481e0318646c401399e94894ff2905e3.dblock.zip.aes
11/28/2018 02:46 PM 424,953,949 duplicati-b85a4e13191424dd5854f959702596779.dblock.zip.aes
11/28/2018 02:47 PM 73,875,021 duplicati-be17f55c4122b437d88787873593279bd.dblock.zip.aes
11/28/2018 02:14 PM 5,725 duplicati-i24839d66428448e7be5b5e0913fac486.dindex.zip.aes
11/28/2018 02:24 PM 135,389 duplicati-i8519202d11fb471cbe80db97cbbc050d.dindex.zip.aes
11/28/2018 02:17 PM 10,349 duplicati-i9b469356746643de9313a7a2dd9eb971.dindex.zip.aes
11/28/2018 02:14 PM 5,677 duplicati-iba7f0e5aefac431089e7835eab131fc8.dindex.zip.aes
11/28/2018 02:46 PM 899,757 duplicati-if988d21898cf4131ac61af020148874c.dindex.zip.aes
11/28/2018 02:47 PM 45,437 duplicati-ifecfa9717b684b9b8b0cb3e8b1be55f0.dindex.zip.aes
I’m glad you’re down to a more reasonable number of files, and with --blocksize=100KB (unlike my intentional 100MB just to see if I could see partial filling), I suspect your stream of dblocks is more fully filled than above.