For nearly a month now, Backblaze has been fixated on a particular file of mine, that happens to be over 1 TB in size. Backblaze seemingly uploads it completely, but then on the next backup it uploads it again, even though it has not changed (in eight years!). Ad infinitum.
Using their Explainfile tool to dig into the log files, the clue seems to be:
- line 288 - 2024-12-16 16:16:17 0000000646 - ERROR: UpdateBzDoneRegardingFlsToBeExp - Z_B_TOO_MANY_CHUNKS bz_done_ line chunk related, numBytesInLargeFile=1099512156951, totNumChunks=104858, bz_done_line_is: 5 ! …
- line 522 - 2024-12-16 16:18:46 0000000646 - ERROR - bz_done_ INCONSISTENCY_FOUND - 20241216161846 - BadBadBadChunkRecord hexAsciiVal=0x78 - AfterBzdoneLargeFileAnalysis: chunkSeq=100001, highestChunkSeqSeen=104857, fileIdOfLargeFile=00000000002c53cd, dateTimeOfLargeFile=20231217091843, XYXBXXX_FILE_NAME: …
Admittedly I’m guessing somewhat, since that’s a rather reader-hostile log message, but the combination of the Z_B_TOO_MANY_CHUNKS error mnemonic and chunkSeq=100001 (because of its proximity to the arbitrary round number 100,000) strongly suggests that Backblaze is imposing a 100,000 chunk limit. Since chunks are 10 MB each, that’s exactly 1 TB.
This is unequivocally at odds with what they claim repeatedly on their website, on pages like What Backblaze Backs Up and File Sizes.
It’s not clear to me why this is suddenly a problem; is this a newly-imposed limit? It’s possible that a month ago I removed some exclusion on the file, but I don’t remembering doing that and I can see no reason why I would have excluded it to begin with. If it is newly imposed, that would imply it’s also retroactive – that Backblaze actually deleted the existing backup of the file from their servers, thus causing the client app to try uploading it again.
I reached out to their technical support, of course, but thus far have only received mindless responses – restart your computer, reinstall Backblaze, etc.
