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Hash fails; Data loss


PhilA

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Is there any way to prevent constant hash fails? I have torrent content which started out fine, but about 40% into it and I get constant hash check failures. It is mp3 music, and so I feel that the tracks overall may be fine anyhow, and I'd like to try stopping the checks, but don't know how. The only thing I can think of is to try to remove all the completed songs, delete the rest of the content, and start the torrent again, deselecting those songs I already have, and hope next time it may do better. Still, that will waste a lot of data.

Another problem, which may be related, is how to prevent continual data loss due to power spikes, Windows crashes, file crashes, stopping and starting torrents, and so forth. Every time this happens it sets me back, and with a large torrent (only happens with those), it then takes an interminable amount of frustrating time to complete, if it ever does. When the last bits may be corrupted, it shouldn't be necessary to rewrite every downloading piece in it's entirety (maybe 4 Mb each). I've lost at least 400 Mb at a time because of this problem. If there's no solution, I would seriously need to consider other software. I don't know if other bit torrent clients would be compatible with the partial downloads at all. Along with the hash failures, I'm losing mountains of data and wasting so much time and money.

It's all a bit mysterious to me. I've only been using it a month.

I'd rather stay with utorrent if I could, as it's given me a lot of joy already. But there's problems which must be addressed, and I don't know for sure what's to blame.

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In general Hash fails are not caused by the torrent client. In other words loading the same torrent in another client and connecting to the same people will also result in the same hashfails. You can try it if you want.

As I far as I understand it the biggest cause of massive hashfails is peers who send incorrect pieces to you. Usually this is done by malicious peers intentionally to mess with the torrent.

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Yes I agree. However it seems strange that I could obtain over 40% before problems started. Then too utorrent started banning peers, but the problem is still occurring with this particular torrent content. The pieces here are 2Mb, which is too big I feel when I'm on restricted bw. If they were smaller, there may be less of a problem? If it is only one bit of corrupt data in the piece that is. How long are peers automatically banned? As this content could take another week, even longer with more hash fails, and I don't want the same peers back again for this file at least.

I was only interested in taking up partial torrents in a different client if I gave up utorrent, as I know I'd be connecting to the same peers.

I also concluded that the makers of utorrent don't want hash checks turned off, as this would be contributing to the spread of bad data. So I guess that's not the answer. It seems that 'diskio smart hash' is a separate thing, as I've tried stopping that. What does that do?

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I read the FAQ on routers/modems, and it appears that mine would be ok (SpeedStream). Unfortunately I have needed to restart the client a number of times due to crashes and the need to reboot at times. I have even reset bans manually. So I now see I may be getting the same batch of bad peers over and over.

Is there a way to keep them banned until the torrent is completed, apart from continuous connection?

One other thing about hash fails is that it occurs regularly with mp3 files which have corrupt bitrates. This br problem is common, especially with certain softwares coding of vbr's, but it may be repairable, or at least the files may still be ok. If these are included in the torrent, it would cause a variable check result, or failure. Thus it seems these files may not be dl'able unfortunately.

The other problem with this is how can I tell which files are causing the problem with these fails? The error message doesn't elaborate. I could then stop the particular file if absolutely necessary, or better if it could be done automatically.

Also, in the case of banned bad peers, could they not just keep changing their IP addresses to get around that?

[MERGE]

FYI I've dl'ed 900 Mb of this torrent, of which 365 Mb was wasted, including 135 hash fails so far, or 270 Mb

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- Keeping µTorrent running is the only way to keep the peers banned, or you can opt to save a list of the banned peers from the Logger tab somewhere and place it in ipfilter.dat (read: tedious)

- I'm not sure what you mean by MP3 bitrates, but they surely have nothing to do with the problem.

- You can tell which file a piece belongs to by checking the piece number, and finding which file(s) that piece contains data for -- you'll know that from the Files tab

- Banned peers can change their IP, sure, but they generally don't

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I mean that the bitrate is corrupted. Instead of being constant throughout a song, or varying according to the musical intensity (vbr), it just varies randomly. This usually happens with faulty software, or maybe other things happening in memory during encoding.

Often a user never bothers to do anything about it. If you've received such files, sometimes they can be repaired by lopping the end bits with software such as mp3 trim.

I've received mp3 files wrapped with WinRar, which do not pass the hash check, and so WinRar refuses to extract them. I either have to repair the zip or extract by other means. I believe this is due to faulty bitrates, which produce random hash check results.

I feel this may also occur with files within torrents, but I could be wrong. If it is happening, then perhaps a lot of peers are going to get banned unnecessarily. Or perhaps if the original torrent has problems, seeding wouldn't have got started, I don't know.

I still don't see how to know which piece number belongs to which song. The files tab only shows which pieces of various files are active, but they're not numbered.

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BitTorrent doesn't care about filetype. It only looks at raw data, and hashes it. If the bitrate changes, that means the data has changed, and that doesn't happen during transfer, so again, it can't be the problem here.

Forgot to say that you need the First piece column enabled in the Files tab to know which file a piece belongs to...

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Thanks very much. That helps. So it means these are just a-holes who are modifying/corrupting torrent data then. These range from 64-86 as the first figure, and also two different IPs starting with 24, plus a couple of others. Of course, this is just the ones who were eventually banned. I'm not sure how to block any though, and wondering if I blocked a range like 64-86 it might also affect legitimate users?

The last 2 banned for this torrent (the only one I'm having trouble with), were just a few minutes ago, and were 68.186.92.10 and 68.116.164.61 There's even 0.0.0.0

Ultima

"Forgot to say that you need the First piece column enabled in the Files tab to know which file a piece belongs to..."

I don't follow, sorry

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You can block ips using the ipfilter.dat file (edit it in notepad, save it, and enable blocking in µTorrent.)

If you blocked a range like 64-86...it would look like this in the ipfilter.dat file:

38.100.0.64-38.100.0.86

That would be very few ips blocked and very unlikely to affect legitimate users.

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yes, but unfortunately those are the initial numbers. I didn't understand. But at least I might be able to block individual ip's. Only I don't have that file. I just got Blocklist manager, so I'll see how that goes. I don't want utorrent blocked! Still getting hash fails from that torrent, but getting good data gradually. Would I need to close utorrent to block those addresses?

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