Media files disappearing from USB memory stick & SD card

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Hi.

I have a MacBook Air running OSX10. Recently I have had problems with movie files (usually .avi & .mp4) disappearing from both a USB stick & a flash memory card. In the case of the card, they are clearly completely gone, as the memory they used to occupy is now free. The stick still shows the memory as used.

Does anyone know a) why this keeps happening & b) if there is any way to recover the files?

I live on a small island with lousy broadband speed, so I have to download everything I want to watch, as streaming is impossible. Having to re-download everything is a pain in the butt, especially as there is the strong possibility it will just get erased again. I have already tried a couple of recovery apps (iSkysoft & Wondershare), but no luck.

I'm not too up on jargon & have only been using a Mac for a few months, so please keep your answers relatively idiot-proof!

Many thanks.
 
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Your Mac's Specs
L2012 Mini, i7 2.6Ghz, 8GB RAM, 256GB SSD + 1TB HDD(fusion), BenQ 32" 2.5k QHD Display
Sounds like your not EJECTING the device before pulling it out of the system. Just because a file shows to be on the USB stick or SD card, doesn't really mean its on it. To understand this you would have to know the basics of a File Allocation Table and file systems. So try using the Eject function and wait for the system to finish doing what it needs to do to the memory devices before pulling them out. When they disappear from Finders or off the desktop. You should be safe by then.

However that said, if you are using the eject function. Ask yourself if you are prone to static discharge from your clothing or your house. The winter months can make the air dry and a good static discharge can erase or corrupt a memory stick as well. Apples with their metal cases make it easy to discharge to.
 
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I always use the eject function when I take things out. However, if I close the Mac to take it into another room or whatever, I tend to leave the stick / card in, so wonder if that could cause it to think the device was removed incorrectly?

I'm lucky enough to live somewhere with no real winter (it was 18c today, which is unusually cold for this time of year) & our floors are tile, so would be surprised if it's static. i used to be prone to it when I lived in the UK, but haven't had any shocks since we relocated.

I did read something on another thread about FAT32 formatted items not liking the transfer of files above 4GB(?) & the missing data is pretty much all TV series I've moved over from my hard drive in bulk, so would definitely be over that limit. However, I checked the files had been properly copied (including playing random samples in Quicktime) before I deleted the originals from the Mac. I might try sending things over in smaller batches to see if it makes a difference.
 
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L2012 Mini, i7 2.6Ghz, 8GB RAM, 256GB SSD + 1TB HDD(fusion), BenQ 32" 2.5k QHD Display
Yea FAT 32 has a 4GB limitation, at least it did last time I checked. Been so long since i tried, not sure if it will even wright to the drive to start with. Or try and mess up.
Do you have to have the thumb drive as FAT 32? Or can you use Mac OS Extended (Journaled) file system? or will to try it and see if it still has this issue. Hey it may just need to be reformatted. So many things to try. That said, I am not sure what the file size limit is on the Mac OS file system. Sure one of the admin or Mac Gurus here can comment. Admittedly I been using computers for 25 years, but I am a new to Mac so I am back in Newb mode.. LOL
 
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MacInWin

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Yep, 4GB is the limitation of FAT. It's in the directory structure, so that's probably why the thumb drive is empty...no way to write the data for the bigger file. Use Disk Utility to reformat the thumb drive (you will lose everything on it) or the card (same warning) and set it to Mac OS Extended (journaled). Once you do that, however, the stick and card will not be able to be read by a Windows machine unless it's reformatted back to something Windows can read.
 

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