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[sapnho]

For over a year I have been watching a strange problem but I was never able to figure out the cause:

My entire music collection is about 700 GB of APE files. My backup is on two separate sets of USB HDDs. When copying APE files from one drive to another, I sometimes get corrupted APE files (verified with Monkey's Audio verify function) which makes the audio file unusable.

Now I heard different stories in the past why that could be and a bad memory stick or bad USB connection was identified in most cases. However, having tried this on several machines, I don't think that's the cause of my problems.

To put it in perspective: Out of 28,000 files when doing a full backup to a new set of HDDs, I would end up with about 50 corrupted files. This happens with decent hardware like Infineon memory sticks, good USB cables and drives. Is there a function to verify the files when copying in Windows? I don't think the problem is APE related but what could it be?

Thanks for helping me figuring this one out! 

[JimH]

Please take a look at some similar problems in this thread:
http://yabb.jriver.com/interact/index.php?topic=24031.0

[Alex B]

You could try SyncBackSE for big copy operations. It has reliable verify and compare tools.

I don't think the APE format itself has anything to do with the problem. Could it be possible that an USB connection can be more unreliable than an internal HD connection? Could it somehow sometimes pass through errors that would not be possible with a standard HD connection?


In general, I have lost my belief in HD technology. I use only internally connected HDs and I have not experienced data copy errors, but physical HD problems are too common.

During this weekend I have reformatted my HDs and copied & backed up all data that my HTPC/media server has. The configuration uses 3 internal HDs that have 800 GB of storage space (200+300+300). For backups I have 6 additional drives (2x200, 4x300) that I try to keep up-to-date + a 300GB spare drive that can be used for temporal data storage during the operations. The amount of used HD space is currently about 750 GB. The amount of data I copied during the procedure was at least about 2.5 TB. I needed to copy my system partition several times because of odd boot problems and faulty HDs. I started the process on Friday evening and it took about 48 hours.

As a result of this operation I am returning two of the HDs. These drives also happen to be my newest drives. One drive is a 200 GB Maxtor that I received about a month ago as a warranty replacement. It was the system drive. It produced several bad sectors and made Windows unusable. Another drive is a two week old 300 GB Seagate that died completely during these copy operations. This Seagate drive has a five year warranty...  

[benn600]

I think everyone is missing the real issue at hand.  How do you collect 700 GB of music?!  I just bought 80 used CDs the other day and paid close to $500.  New would have been twice that and that only accounts for about 1000 songs or maybe 25 GB.  Granted we have close to 500 total and I am not finished yet, I dout I will pass 200 GB and that is thousands of dollars.  Do you truly own that many CDs?  How does Media Center handle your what, 25K songs?

[sapnho]

You could try SyncBackSE for big copy operations. It has reliable verify and compare tools.

A tool like that sounds like the only way to really make sure that the copy process has been successful. I'll have a look into that.

And yes, MC handles 28k+ files with no complaints from my side.

[Matt]

I'd guess you have a stick of bad memory. 

I recently had the same problem.  It was slippery because I could only get the memory to flip-bits in dual-core stress tests in Windows. (not from single-core bootable memory tests)

Try running two of the free tools here for a few hours: (each with half your memory)
http://hcidesign.com/windows/

Good luck.

[Alex B]

Thanks Matt,

I have run my main MC PC for a long time with certain high speed Bios settings. This dual core test system forced me to loosen the memory timings a bit. According to the other tests I have run previously my too tight settings were good.

Luckily my APE files seem to be fine.

[JONCAT]

I may be in the same boat. My system isn't cranked but tightened up a bit since the 64bit systems really don't operate in the same fashion as the previous "high as you can get FSB" of 32bit was. I used Prime95 and the newest bootable memtest86 w/o errors so I am curious about this app; haven't run it yet. I have had a bad stick as Matt has and corrupted quite a few ape files a few years ago....what a pain. I keep telling myself I will test my memory every few months; we really all should since you never know when a stick is going to bite the dust. We're supposed to load two instances of this tester?

DC

[GHammer]

For Matt:

Is there any way to access the md5 hash outside running the GUI of Monkey's Audio?
Be a handy thing to run against my whole library if there is. Of course, if the file was corrupted when encoding that wouldn't help, would it?

[Matt]

For Matt:

Is there any way to access the md5 hash outside running the GUI of Monkey's Audio?

The MD5s are out-of-order and don't include the tag.  You'll need to use Monkey's Audio itself to check them.  My home computer does about 3 files per second.

Be a handy thing to run against my whole library if there is. Of course, if the file was corrupted when encoding that wouldn't help, would it?

The original input data is CRC'd.

During decoding, the output is also CRC'd and matched against the original CRC.

However, there's that old saying "junk in equals junk out."  If MC tells an encoder "write ABC" and the memory flips some bits so it says "write BAC", there's just no defense.

That's why it's important to make sure your computer memory isn't doing that. (or possibly why ECC is worth it)

[Alex B]

We're supposed to load two instances of this tester?

If the Task Manager shows two CPUs, like in this screenshot:



This is what I did:

- Started the Task Manager and checked the available physical memory
- Started the first test with half of that memory
- Started the second test with "All unused RAM"

[GHammer]

That's why it's important to make sure your computer memory isn't doing that. (or possibly why ECC is worth it)

A fine idea. I am getting a new motherboard soon and will get something that supports ECC.

[modelmaker]

I think everyone is missing the real issue at hand.  How do you collect 700 GB of music?!  I just bought 80 used CDs the other day and paid close to $500.  New would have been twice that and that only accounts for about 1000 songs or maybe 25 GB.  Granted we have close to 500 total and I am not finished yet, I dout I will pass 200 GB and that is thousands of dollars.  Do you truly own that many CDs?  How does Media Center handle your what, 25K songs?

It takes time! After 3 1/2 half years of using various versions of MJ/MC, I've got 40K+ tracks on my HDs. Sources have included ripped CDs, digitized LPs, and high quality downloads and even some reel-to-reel and cassette tapes.

KingSparta has tested MC with more than 150K tracks with no problems.

[hit_ny]

Ran memtest overnight

0! errors

[dlone]

Memtest is great, but only as long as the errors are coming from the memory 

About six months ago I had a pc that had a nasty problem
If I copied a file larger than 256Mb over the network it would get corrupted
Eventually I found out that on every 256MB boundary, one byte was changed to the value 255 ($FF hex)
It finally turned out to be a faulty network chip and changing the network card fixed it
Sadly I'd corrupted a lot of data, which was only shown up by an MD5 checksum
I'd guess that anything the data goes through could suffer from a hardware problem like this

Now I work on the paranoia principle
The first few times I move anything anywhere I check afterwards that it's exactly the same

[GHammer]

Another good tool for testing memory is from Microsoft.

MS Memory Tester

[hit_ny]

Ahh, MS mem test has the possiblity to run from a bootdisk, so you can test the area occupied by the OS as well. for FREE!

Not that you can't stick memtest on bootable cd-r, bit more involved tho, Barts PE etc