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Topic: .rar files corrupt over time (Read 6846 times) previous topic - next topic
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.rar files corrupt over time

I am aware that this has been posted about before, and that the conclusion is that no filetype can become corrupt over time. However, I have an archive of all my installation files including audio, kept in winrar files on secure servers with mirrored disks. Whenever I install a new program, I keep a .rar archive of it. I check the integrity of each .rar file before leaving it on the disks. I check the quality of RAM using Memtest on over 8 passes before installing ram, to make sure it reports 0 errors.

Despite all my precautions, I have noticed that over time, .rar files will become corrupt. Files which I last opened several years ago, have a higher chance of corruption than recently archived files. However, recently archived files are still sometimes corrupt, rendering them useless.

The general rule that I have noticed is, the longer I leave the files, the higher the chance of their corruption. As I cannot afford to loose project data, I have now stopped archiving to .rar files.

Now, I hear you say: "This is due to a hardware fault!" - This is the logical conclusion, However, the archive is kept on mirrored HDs, on 2 separate, different computers, one of which was built by myself. I am extremely thorough building and maintaining PCs, and run routine maintanance tests.

Since years ago, I have still found no real reason for these corruptions. Heck- I also keep a copy on of important data on 2 separate HDs on a shelf in a different building, inside a case, in case of lightning strike or fire. The corruptions have been found to occur at an equal rate on unconnected HD, despite never being used. This should not happen.

The only consistent factor in this problem is the medium type (HD). I have not noticed this issue with DVD or CD storage (yet). I do keep archives for a longer period of time than most home users, so if anyone is likely to notice this, it would be me. With the kind of thorough checks I perform, this should not happen.

I just thought I'd post this because, I now find myself stumped by this issue, and having to re-think my pre-conceptions. In the words of Sherlock Holmes, “Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth.” . Perhaps there is an as yet unrecognised vulnerability with HDs and .rar files..

I won't be archiving to them again, and would not advise others to.

.rar files corrupt over time

Reply #1 –
[deleted]

.rar files corrupt over time

Reply #2 –
Most likely cause: RAR files contain information that allows them detect when they become corrupted. Normal files do not.

Hence, everything is really getting corrupted somehow,  but you only notice it for the rars.

.rar files corrupt over time

Reply #3 –
add a 5% recovery record to the old .rar files, that should help alot.
if you really dislike it now, you should look at the format the newsgroups use for their er.. endeavours. I thinks it's .pak ? I is highly error resistent.

I'm using RAR since version pre-1.5 (MS-DOS) and it never befaulted me

.rar files corrupt over time

Reply #4 –
Quote from: TrNSZ on
Your RAR files are getting "singled out" and corrupted on unconnected hard disks?  Sounds too funny to be true.

My oldest RAR archives that have been stored only on HD are from 1998, and haven't corrupted themselves yet, and it's been what, 8 years now?  Maybe you have some kind of horrible radiation or magnetic fields in your area?

Get out the tin-foil hat.


I have moved 3 times over the years, and the results are the same in all areas.

Quote from: Garf on
Most likely cause: RAR files contain information that allows them detect when they become corrupted. Normal files do not.

Hence, everything is really getting corrupted somehow,  but you only notice it for the rars.



.exe files will not install if they are corrupt. However, the .exe files are fine when not inside a rar.

However, you bring up an interesting point. It is possible that HD is an unreliable storage solution. However, I have these things saved on mirrored Disks, which rules out time/file degradation. They are checked before being encoded, and then left unopened for years; which leaves out faults during the .rar save process. RAM is checked with minimal 8 passes (usually around 15), with zero faults, which rules out RAM as a likely cause of so many corruptions. Upto date virus protection from Panda, rules out viruses corrupting filetypes.

As an additional caution, I am not going to use the HD medium where ever possible. To back up important data, I will now start using DVDs, with uncompressed original file formats. Unless anyone has any other suggestions..

.rar files corrupt over time

Reply #5 –
Quote from: sony666 on
I'm using RAR since version pre-1.5 (MS-DOS) and it never befaulted me


I have heard of people having good experience with Maxtor Hard Disks. In contrast, I have used 11 Maxtor HDs of various grade models in different areas, and in all cases 100% of them have failed/crashed quickly, on different computers. I have never experienced a problem with Western Digital HDs, so I now use them and so far they have lasted twice as long as the Maxtors and still no problems. The only consistency here is the make- Maxtor. I cannot explain why other people would have different experiences from me, other than the fact that we are dealing with probabilities and statistics here. Problems are more likely to be highlighted by someone who uses these things more.

My point, is that this is not a one-off, and altering my approach to a solution based on the one-off experience/data of others, has resulted in continued failure in the past. I have no explanation for this, other than perhaps some people are less vigilent or observant, or perhaps there is some unknown force at work. Either way, my aim is to solve the problem and I will go with the most likely method to solve it. I am interested to see if anyone has any reasonable explanation/hypothesis for what's happening.
 

.rar files corrupt over time

Reply #6 –
In the 20+ years I have been doing IT, I have seen more Maxtors fail than any other brand.
The mean time between failure for a hard drive is too short to be used as a backup.
CD, DVD, or tape are considered good enough for archiving.
There are bearings, mechanical components, and lubricants in a hard drive that can dry out or seize.

Edit: Spelling

.rar files corrupt over time

Reply #8 –
The only time I've ever come across a .rar archive of my own that was "corrupted", but not really corrupted because it was WinXP itself causing the problem because my full system backup had exceeded 4GB inside of the archive. WinRAR would choke on that archive, etc.

After running a full surface error scan using Check Disk CHKDSK /R D: it must have corrected something, and then WinRAR was able to verify the archive as alright with no errors. However I quickly unpacked that backup and then split it into four separated .rar archives "parts" and haven't had any issues since then either from WinRAR or Windows, nor has Check Disk had to correct anything.

.rar files corrupt over time

Reply #9 –
Is there a possibility of some kind of background program sabotaging the .rar files?

I also have some very old RAR files since ca. 1992 that are still good. It stays in my HD, and everytime I upgrade I did a full copy to the newer HD.

Or it might be that the controller/drive is failing imperceptibly. I read a thread in HA somewhere that -- despite the stigma attached to Gibson -- SpinRite is actually good enough to check HD low-level circuitry in action.

BTW, I second sony666's suggestion: Add recovery record. If the RAR files never leave your HD, you can get by with 2%. If you decide to copy them to CD's or DVD's, then use 5%.