files disappearing after copying to usb drive

Question

lchiesi Author

Level 1

8 points

files disappearing after copying to usb drive

hello,

when i copy a certain number of files from my hd to a usb stick,

some files are not copied, usually ONE gets skipped, sometimes TWO.

i tried several times, and it keeps happening. i searched the forums to no success

(something is mentioned about samba server that looks somewhat the same).

this is the scenario:

OSX10.6.7

SANDISK CRUZER 32 GB

i drag a considerable number of files (>50) to my usb sticks (tried with two different sticks, one

encripted with Truecrypt, one not encripted).

the progress bar looks ok, the number of files that are being transfered matches with the files

that i actually highlighted (from a search results window in finder).

but when the process reaches the end, one file is missing (sometimes two files are missing)

from the destination directory.

i then check the original files and none is damaged or corrupted.

in fact, if i redo the whole process to a new destination directory, one file is again missing, but ANOTHER file, at random.

proof that files are not corrupted is that if i manually copy the missing file it gets copied ok.

i am really flubbergasted.

it is such a simple scenario, yet such a serious bug.

anybody with the same problem?

any help?

Mac OS X (10.6.7)

Posted on Jun 4, 2011 10:55 AM

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Answer 1

sig

Level 8

35,862 points

Jun 4, 2011 4:49 PM in response to lchiesi

The files may be OK but the media on the flash drive may not be. Try re-fomatting it and try again.

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Answer 2

Kurt Lang

Level 9

61,908 points

Jun 4, 2011 5:07 PM in response to lchiesi

You may have illegal characters in the names of the files that won't copy.

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Answer 3

lchiesi Author

Level 1

8 points

Jun 5, 2011 1:50 AM in response to Kurt Lang

hi, thnx for your replies.

@sig

I tried on two drives, and it still happens; tried reformatting, still happens.

@kurt

no illegal chars; just plain photo files: same name in a sequence, such as

DSC00991.JPG and so on.

as i said when i identify the missing file and just copy that to the destination

folder, everything works just fine.

this only happens when i copy a number of files that is >50.

i have tried with lower numbers and it does not happens.

i suspect it has to do with the copying process, and how it is handled

by the system.

if i keep looking at the status bar, while

the files are being copied that is what i see.

suppose i am copying 104 files:

the status bar displays "104 items" until a split second after the process is completed

then the number changes, and the status bar goes

"103 items".

no error, no dialog, no nothing.

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Answer 4

Csound1

Level 9

60,027 points

Jun 5, 2011 6:12 AM in response to lchiesi

On the source: open one of the files that did not copy, open the original.

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Answer 5

lchiesi Author

Level 1

8 points

Jun 5, 2011 8:44 AM in response to Csound1

@Csound1

yes, i did open those files: they are just fine. they open just fine; not corrupted; nothing wrong about them.

and to make things more weird, the files that do not get copied are different every time.

as i said, if i copy them manually, they get copied ok.

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Answer 6

Csound1

Level 9

60,027 points

Jun 5, 2011 8:55 AM in response to lchiesi

OK, it's officially weird, no more suggestions for the moment but I'll think about it some more.

PS: can't replicate it in a short test with 200 files.

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Answer 7

Kurt Lang

Level 9

61,908 points

Jun 5, 2011 12:53 PM in response to lchiesi

Hmm, weird is right, Csound1. I can only think of a couple things that haven't been mentioned.

One, how is the drive formatted? Technically, it shouldn't make any difference if it's FAT32 or Mac OS Extended, but ya' never know.

Two, how often has this drive been written/erased? All flash drives (which includes the new SSD internal drives) have a limit to how many times they can be used before they start failing. Is the drive fairly new, or has it seen a lot of use?

You do have to use them a lot to hit the general limit. This from Wikipedia:

Longevity

Barring physical destruction of the drive, the memory or USB connector of a flash drive will eventually fail. SLC based memory is good for around 100,000 writes; more commonly used MLC for around 10,000. The USB connector can withstand approximately 1,500 connect/disconnect cycles.

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Answer 8

lchiesi Author

Level 1

8 points

Jun 5, 2011 1:20 PM in response to Kurt Lang

1) i have two sandisk cruzers 32 gb.

both FAT32, one encrypted with truecrypt.

2) one drive is brand new. the other has been used

for a while (over a year). but i use it on several computers

(PC included) and have never noticed any sign of weird behavior.

as a side note, what really really baffles me most is that

i do not get any feedback: no dialog, no error. shouldn't there

be basic controls on such a fundamental action as copying files?

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Answer 9

Kurt Lang

Level 9

61,908 points

Jun 5, 2011 1:56 PM in response to lchiesi

one encrypted with truecrypt

1) You don't say which one. Would it be a safe guess that it's the drive you're having trouble with? I see TrueCrypt has an OS X version, but I would have to believe they don't intend for users to mix systems. In this case, the Mac OS, with a Windows formatted drive. Which may also relate to this:

as a side note, what really really baffles me most is that i do not get any feedback: no dialog, no error.

Which wouldn't surprise me since encryption is going on at the same time with software that is not only third party, but dependent on the skills of people who simply donate their time to write it. Not that there isn't good software out there like this, but something that has to meld as closely as encryption software would with the OS would mean they need to know every single bit as much about Apple's drive specification and OS as Apple themselves. Small errors in reporting back a write into an encrypted space could be why OS X is saying nothing.

2) Nowhere near enough use for even the year old drive (with average use) to be wearing it out.

shouldn't there be basic controls on such a fundamental action as copying files?

There are, but again, TrueCrypt could be the whole reason copies aren't working the way you expect. Of course, this is all a wasted hypothesis if the drive that isn't working isn't the one using TrueCrypt.

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Answer 10

Csound1

Level 9

60,027 points

Jun 5, 2011 1:53 PM in response to lchiesi

Yes, I would have expected an error on failure, obviously this is not registering as a failure, even more fraught!

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Answer 11

lchiesi Author

Level 1

8 points

Jun 5, 2011 3:42 PM in response to Kurt Lang

You don't say which one. Would it be a safe guess that it's the drive you're having trouble with?

unfortunately not. it happens on both drives.

as to TRUECRYPT: well, it is a very robust piece of software, and

has a wide community of users. that was the first culprit i thought

of. but, alas, no (also, no mention of a problem like that on truecrypt

forums, which are fairly well attended).

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Answer 12

Kurt Lang

Level 9

61,908 points

Jun 6, 2011 5:52 AM in response to lchiesi

Don't know how easy this would be for you to do. Can you uninstall TrueCrypt for the moment and see if anything changes? Not to harp on that piece of software, but I've never heard of anyone having this issue before, which makes it seem like a logical place to start.

Or, try reinstalling Snow Leopard and then apply all available updates. Create a backup first, just in case. Any difference?

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Answer 13

lchiesi Author

Level 1

8 points

Jun 6, 2011 8:51 AM in response to Kurt Lang

since it all happens on a non encrypted drive too, i don't see how we could blame truecrypt for that.

also, i would think of reinstalling OSX only as a last resort. it is such an extreme measure that i don't

consider it at the present time. and frankly, my MBP is fairly new and haven't really done anything to

its system (have installed very few things; it is pretty much in its original state) and that leads to think

that reinstalling the os would not do too much good to my problem.

doesn't anyone see any connection with this thread?

https://discussions.apple.com/thread/1429064?threadID=1429064&start=0&tstart=0

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Answer 14

Kurt Lang

Level 9

61,908 points

Jun 6, 2011 9:07 AM in response to lchiesi

since it all happens on a non encrypted drive too, i don't see how we could blame truecrypt for that.

Not specifically trying to blame TrueCrypt, but it's the only item mentioned that could affect the operation of the OS in such a way. Whether a particular drive you're writing to is encrypted or not may not make any difference if the add on is causing OS X to function incorrectly overall.

Reinstalling Snow Leopard is as easy as reinstallation of the OS has ever been. No "Previous System" folder is created. All of your third party apps, preferences and settings stay just as they are. Just the files normally installed from the OS X install disk are replaced with fresh copies. Still a bit time consuming, but pretty easy overall.

My main purpose in having you remove TrueCrypt (at least temporarily) was to try and eliminate it as a possible cause of the problem. Without doing so, we can't know, and therefore can't be sure it isn't the issue.

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Answer 15

Linc Davis

Level 10

209,649 points

Jun 6, 2011 9:20 AM in response to lchiesi

since it all happens on a non encrypted drive too, i don't see how we could blame truecrypt for that.

We could blame TrueCrypt for it because TrueCrypt includes a kernel extension that is always loaded and always affects the way the operating system works, even when you're not using a TrueCrypt container. If you want to solve system problems, you have to take a systematic approach. Skipping a step because you think it's not necessary will lead to failure.

You don't have to uninstall TC in order to rule it out as the cause. Boot in safe mode and test.

Mac OS X: What is Safe Boot, Safe Mode?

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