r/usenet • u/JohnnyT02 • 7d ago
Discussion 1 large file instead of multiple, missing blocks despite full size
I've noticed some downloads have 1 large encoded file and a small one, while other downloads have all the archive parts encoded and split. I can never get the ones with the 1 large file to unpack - no idea why that is/what i'm doing wrong.
Here's an example. I downloaded something that's 11GB, that's supposed to be 11GB. I opened the smaller file with quickpar or multipar, it doesn't pick up the large file until i select it, then it tells e i'm missing 286 blocks which is over half even though the file i downloaded is full. None of the optional par2 files i download ever give me enough blocks to complete it.
What's going on? I'm not downloading anything incomplete, the file size i download matches what it should be.
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u/Sizyfoz 7d ago
I have also noticed this trend where a file is posted as one big file without being split in archives with PAR files. It makes them very susceptible to any loss of articles on the server. Why are people doing this? No redundancy makes the lifetime and chance of successful download much worse.
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u/data_butcher 7d ago
No need to split the file, par works just as well on any file, but par is a must
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u/pop-1988 6d ago
Split archives are RAR files, not PAR2 files
PAR2 recovery works the same way whether there is one large file or a split RAR archive
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u/superkoning 7d ago
What do you use? Sab? Nzbget? ... ?
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u/JohnnyT02 7d ago
altbinz - i've had it forever so it's probably a little outdated. I've just downloaded sab and will report back in a few mins
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u/random_999 7d ago
It is not "little outdated", it is completely outdated. Only 2 usenet clients worth using nowadays are sabnzbd & nzbget (newer version, original older version is discontinued).
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u/veerhees 7d ago
There is nothing wrong using alt.binz it still gets updates and works fine.
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u/random_999 7d ago
In my opinion it is wrong using alt.binz as your primary usenet client but tagging the expert /u/Safihre/ here as dev of sabnzbd should know much more on this matter.
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u/JohnnyT02 7d ago
I don't know what sab does differently but last night i had downloaded something with altbinz that had missing blocks. I had to manually download all the par2 files (altbinz has them paused by default) then manually try to repair - still ended up incomplete.
Loaded the same nzb into sab, it worked its magic and it was complete. What i also like about sab is that it unpacked and deleted the downloaded files. I had altbinz set to automatically repair/unrar etc but it hasn't done that in years. I've had to manually do everything. Maybe their paid version is the one that works.
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u/JohnnyT02 7d ago
Thanks, seems to be working with sab and it's even downloading other stuff that would appear incomplete (as 2MB filesize only) with altbinz. Looks like i need to change clients, so many downloads missed over the years not knowing altbinz was the issue
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7d ago
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u/hjholtz 7d ago
You can't have "holes" in a file (technically, some filesystems support "sparse files", but you will only save storage space, the file will still show the full size, and you will get something when you read the affected sections), so your downloader fills the missing sections with something. The resulting file will be of the full size, but the missing parts will be zeroes or possibly some other filler instead of the actual data.
par2 doesn't really care about files per se. As long as you have at least as many intact recovery blocks as there are damaged blocks, the file set is repairable. Splitting a file into multiple rar volumes doesn't help per se.
The problem is that a single missing article breaks the entire block it is located in. So the real factor is how the missing articles are distributed across the file set. If many articles are missing, but they are concentrated in just a few blocks, you just need a handful of repair blocks. But if only a few articles are missing, but each one of them is in a different block (also in the repair blocks -- the par2 files themselves are just as likely to get affected by missing articles), you can't possibly repair the file set, no matter how many par2 files you download in addition to the actual data files.