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Warning: WinRAR bug ???

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Carol Haynes:
Strange behaviour.

I have a repeatable problem with WinRAR ...

There is a fairly large collection of PhotoShop tutorials in a series of nested folders on my hard disc. I have checked the disk thoroughly and there are no errors. When I use the Wondows Explorer context menu extension to compress the entire folder structure into a RAR file it all seems to go well (except it takes a long time). However, when I test the RAR file it comes up with a number of CRC errors.

I have repeated this a number of times and it happens every time.

It does not happen if I use WinZIP to produce a ZIP file and then use WinRAR to test it.

Odd, I know, but there must be something odd happening with this particular data set.

All I can say is if you rely on WinRAR (which I have for a long time) run a Test to confirm archive integrity after creation. It may be an odd problem that doesn't appear often, but you can guarantee it will be the one archive you need that is affected!!!

aignes:
There is a fairly large collection of PhotoShop tutorials in a series of nested folders on my hard disc. I have checked the disk thoroughly and there are no errors. When I use the Wondows Explorer context menu extension to compress the entire folder structure into a RAR file it all seems to go well (except it takes a long time). However, when I test the RAR file it comes up with a number of CRC errors.
--- End quote ---

Do you refer to the "Test archived files" feature in the "Archive names and parameters" dialog, or do you test the archive after creation with "Commands+Test archived files". And do you run into the same problems when you use the Zip compression method in WinRAR?

I use WinRAR since years and never experienced a problem with it. But I think I should test my archives in future, it's probably a big mistake to rely on backups without testing them  :-\

Just a thought, but could probably a damaged file or a hard disk failure confuse WinRAR that way?

mouser:
carol, it would be nice to know if the bug is in the archiving or the crc reporting.
maybe you can extract the files that report bad crcs and then compare and see if they really are damaged.

Carol Haynes:
Out of curiosity I rebuilt the archives planning to test the unpacked integrity using Beyond Compare. Here are the stats:

Original Folder size: 802,014,370 bytes (1101 files, 137 folders)

WinRAR 3.50 archive size: 737,140,770 bytes
Time take to build: 39 minutes
TestResult (WinRAR): Frustratingly Good (Sod's law at work)

WinZIP 9.0 SR1 archive size: 753,862,116 bytes
Time taken to build: 5 minutes
TestResult (WinRAR): Good

I don't know why it worked this time ... I did exactly the same thing the other day 3 times and every time the RAR file had bad CRC results. Trouble is it then won't let you extract beyond the bad file (it just says the RAR file is damaged).

To be fair on the poor compression results the folder set consisted of lots of files, many of which were already compressed with ZIP, RAR, CAP, GIF or JPEG. There were also a lot of PhotoShop files, PDF files, .EXE files as well as a lot of text/HTML etc. Given the number of precompressed files the compression rate is to be expected.

It is interesting though to look at compression times for these files !!!

It is also interesting that the ZIP file tested a lot quicker too.

Nighted:
Incase you're unaware, WinRAR 1.51 has been out for a good while now. Try upgrading.

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