About CRC Errors

[shypike]

Did that... When the download has been succesfull (without crc failures) the commandline par2 and unrar work perfectly, when there were failures par2 sometimes is able to correct, sometimes not. The disk seems to work OK.

BTW: do you use a multi-code version of par2?
I'm not sure what you mean...

What do you mean by CRC errors? Are warnings about articles that have CRC errors?
Or is is that unrar reports CRC errors?
The proper test would be to take an NZB, remove a few articles from it, let SABnzbd download it without post-processing.
Then run "par2 r" from the commandline and unrar too.

There's the classic par2 by Peter Clements and there's a mulit-code version by chuchusoft.
The latter sometimes gives trouble.
You can see when you just type "par2". When you see only Peter Clements name, it's classic one.
Other versions will have other names added, like chuchusoft.

BTW: unrar doesn't have a spotless reputation on Linux either.
The ones from the repositories are notoriously weak, especially the "free" ones.
Make sure you use a very recent one downloaded directly from the rarlabs site.
http://www.rarlab.com/rar/rarlinux-3.9.3.tar.gz

[tpas]

Hi,

Sorry for the late reply, sometimes have to do other stuff...

Off course the unrar reports the crc errors. But it only reports crc errors when I download to the raid array. If I download THE SAME nzb file to the single harddrive, no crc errors occur and most of the time no repair has been necessary.
The par2 repair also did not correct those crc errors.
The par2 program that I use is the one from Peter Clements.
The unrar is the one from rarlab, only in my install it was version 3.90 in stead of 3.93. Updated now, but doesn't improve very much.
I keep suspecting the download part writing to the raid array being the main cause of the problems, and then par2 being unable to repair the caused faults, and then unrar detecting crc failures.

[shypike]

There's only one way to find out.
Let SABnzbd download the same NZB once to the single drive
and once to the RAID, without any post-processing.

Then compare the files on the byte level. If there are differences,
then  it's something in the OS, Python or SABnzbd.
If the files are identical, bit manual par2 and unrar do present problems,
then it's one of these.

[tpas]

There's only one way to find out.
Let SABnzbd download the same NZB once to the single drive
and once to the RAID, without any post-processing.

Then compare the files on the byte level. If there are differences,
then  it's something in the OS, Python or SABnzbd.
If the files are identical, bit manual par2 and unrar do present problems,
then it's one of these.

Good idea. Will try it and report back to you. Thanks for your neverending replies!

[guitarboy]

After a long stretch where I had very few CRC errors, I'm starting to see them much more frequently.

I recently added an Nvidia graphics card - could that be causing the problem?

Has my host (NewsDemon) suddenly become more flaky?

The problems also started when I upgraded to SAB 0.5.4, but that happened around the same time that I installed the Nvidia card so could be a coincidence.

Usually the error does not occur again if I repeat the download.  Right now I don't have caps on my bandwidth, so it's easier to d/l again rather then fuss with par2.  But it's still a big nuisance.  Is there an easy way to fix these errors without downloading the entire RAR set again?

[shypike]

Is there an easy way to fix these errors without downloading the entire RAR set again?

There will be a retry feature in release 0.6.0

[pobox]

Mr. Guitarboy received some suggestions in his old topic #3408 What to do with CRC errors?

What type of CRC error, #1, #2, #3, or #4?  That must be determined first.  This case seems to be #1.

After upgrading, make sure Post-Process Only Verified Jobs is turned on.

Check possible bad RAM with Memtest.

What do retrys accomplish?  Could it be the kind of workaround that is just an ugly brute force method?  If there's an issue with NewsDemon it should be identified, called to their attention and fixed.

[MageMinds]

Hi, since the beginning of last week I began to have a lot of CRC errors, I even disabled the Quick-Check and still had CRC error while decompressing, the manual verification of the par2 revealed almost every time bad files, that where able to be repaired and decompressed manually, but not every time.

Then I ran memtest86+ v3.5 to reveal a bad RAM module... Time to RMA this RAM module now... Lifetime Warranty come in handy now! :-)

MageMinds

My computer is running slooooooow with only half it's RAM in single channel

[Sharpey]

Hello all.

I only yesterday discovered newsgroups.  I was recommended sabnzbd and astraweb (seems this was a bad idea!).  

I have downloaded a large file and it has begun verifying (which is taking a long time).  I clicked on the first .rar (before verifying is complete) and I get an error message about 'unexpected end of archive' or something.  

What I want to know is, that when verifying is complete, will it have fixed this archive or have attempted to?  Because I have spent hours downloading this file and it is going to take a long time to verify as well so if I am screwed already then I will just stop and delete it now.

I am a novice with this sort of thing so if you require any more information please specify and I will provide it.

I appreciate any help.

Version: 0.5.6 32
OS: vista home basic
Install-type: Windows Installer
Skin plush
Firewall Software: kapersky
Are you using IPV6? not sure
Is the issue reproducible? not sure


UPDATE

Verifying has finished (took almost three hours!  ) and it said 'Repair failed, not enough repair blocks (1063 short) '

It then downloaded another 6-700mb.  It then started to repair or something, and now it is verifying again.  Surely it is not going to go through another three hour verification?!  What if it still doesn't work after that?

Can anyone give me some guidance please?
Any tips on how to avoid such a situation in the future?  Spending five-six hours to download something and then a few more hours to verify for it to then not work is not exactly ideal.

[shypike]

Verifying has finished (took almost three hours!  ) and it said 'Repair failed, not enough repair blocks (1063 short) '

On slow systems verification (more probably repair) can take a very long time.
Sometimes you just don;t have enough data.
That's just the way it is with Usenet.
If you have quality NZB files (and a good Usenet provider), a minority of downloads will need repair.

[Sharpey]

Thanks Shypike.  I have researched further and I will check NZBs before I start to download them.  I have also enabled backup servers.  Also, I have heard that older files might have all parts included but not necessarily intact 100% so I will look to more recent files.

[shypike]

Thanks Shypike.  I have researched further and I will check NZBs before I start to download them.  I have also enabled backup servers.  Also, I have heard that older files might have all parts included but not necessarily intact 100% so I will look to more recent files.

If you use one of the well-known providers,. be aware that these get DMCA notices and
will subsequently (partially) remove stuff.

[JoshFink]

I'm probably missing something very straightforward but hopefully someone can help.

I checked #1-#3.

I set the files to download and I've noticed that 80% of the  downloads seems to get an CRC error.

I've also noticed that the par files are gone when I check the directory. I know they were there when they were downloaded.

The logs just state

2010-12-30 16:15:23,210::WARNING::[newsunpack:505] ERROR: CRC failed in

Any ideads?

Thanks

Josh

[shypike]

I'm probably missing something very straightforward but hopefully someone can elp.
I checked #1-#3.
I set the files to download and I've noticed that 80% of the  downloads seems to get an CRC error.
I've also noticed that the par files are gone when I check the directory. I know they were there when they were downloaded.
The logs just state
2010-12-30 16:15:23,210::WARNING::[newsunpack:505] ERROR: CRC failed in

You can get CRC warnings during downloading. These can be ignored, because they are either
irrelevant or will be repaired later.
The CRC message that you list is coming directly from unrar.
It means that one or more RAR files are corrupt.
The PAR files are gone because the par2 check concluded that the files are OK.
That you still get a CRC error has two possible causes:
A corrupted upload or defective hardware.
Maybe you can try to unpack the file on another system?
If you still get the same error, the upload was corrupt.

[JoshFink]

Thanks for the tips.

One thing though. I re-downloaded the par files that were deleted and ran unpar manually and everything fixed up fine. I did this for all the files and there were no errors at all. Now I did use QuickPar instead of the built in par2 could that be the problem?