-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 The Friday 2006-12-08 at 10:27 -0500, Anthony Bryan wrote:
aria2c finished the download with a checksum error - suposedly metalink had strong advanced error correction methods to avoid this very thing, but it doesn't work :-(
I'm very sorry you had a negative experience with metalink. (Hope you will have good ones in the future, when you are ready to try again).
Downloading ISOs, spending all that time and bandwidth, and ending up w/ errors is very frustrating. I've been there, and that's one thing I've tried to fix w/ metalink. Unfortunately, metalink clients don't do magic yet and can only work with what information they have.
Regarding error correction: Some metalink files contain no full file checksums, some contain full file checksums, some contain segment AND full file checksums, and some contain FTP/HTTP mirror links AND torrents.
The segment checksums allow portions of the download with errors to be discarded, and faulty mirrors as well. Only the portions that had errors will need to be re-downloaded - aria2 doesn't support this yet. metalink clients that support torrents can use the error correction of the torrents on data received from FTP/HTTP mirrors.
Too bad. I was misled to think this was handled properly.
The openSUSE metalinks at http://download.packages.ro/metalink/opensuse/ only contain mirrors and full file checksums. (Note: These metalinks are not generated by me). This means metalink clients will download from the mirrors, and basically run an automated 'md5sum filename' once the full file has transferred - this is more verification than error correction, because it only tells you if the file is exactly correct or wrong. With a full file checksum, you still have to re-download the whole file all over again if it doesn't match.
Too bad of Novell not to prepare partial chunk checks, but that would have been useless as aria2c doesn't support it.
I started it again to check, and it destroyed what was downloaded, starting from zero! :-//
Definitely a bug in aria2, please report it at their page: http://aria2.sourceforge.net . I haven't seen that happen before.
I'm so... disgusted that I don't think I'll bother. There it was the downloaded file, with an error somewhere, and when I restarted aria2c, instead of rechecking, or telling me that it was complete, it overwrote it with zeroes and started to download from the start. No warning! I know how to repair a download with errors, but I had no chance to try. So I have started again with btdownloadcurses, which is going three times slower than aria2c.
I'm sorry, but I have to recomend not to use metalink, nor aria2c. This is not ready for primetime, folks. I'll stay with torrent, thanks.
Details and technical answers to the opensuse list, please.
When you say that, it translates to "I have to recommend not to use FTP/HTTP mirrors" since that is what aria2 is doing. FTP/HTTP is not error proof, there will be errors in transfers. One error in a whole 3GB transmission means the full file checksum will not match.
Yes, but: I had assumed that the proclaimed reliability of the protocol meant that this was handled somehow: if a chunk is in error, repeat download of that single chunk. The end result most be perfect. If there is no chunk testing in aria2c (wxdfast did not work at all), and the metalink file (from Novell) contains no chunk info, this is no better than plain ftp or http (or even worse if a single mirror is broken and not traceable). I'm not testing it again till this is solved, sorry. If I had been bitten with a smaller download I would not be so disgusted. - -- Cheers, Carlos E. R. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (GNU/Linux) Comment: Made with pgp4pine 1.76 iD8DBQFFeYyntTMYHG2NR9URAvXbAJ95sJuHHRbdetgnSkdec8woHBX9DgCdHUFT 1do++fbcLWZU66avENw2tE4= =F+Ob -----END PGP SIGNATURE----- --------------------------------------------------------------------- To unsubscribe, e-mail: opensuse-project+unsubscribe@opensuse.org For additional commands, e-mail: opensuse-project+help@opensuse.org