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32gb FAT32 SDcard to 64gb exFAT SDcard Problems

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By ultimatdan, Senior Member on 5th July 2014, 05:24 PM
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Ok so i've been using the SanDisk Ultra 32GB MicroSDHC Class 10 sdcard in my note 2 and when i filled it up i then went out and bought the SanDisk Ultra 64GB MicroSDXC Class 10 UHS sdcard. I want to transfer everything thats on that 32gb card to my new 64gb and keep going. Obviously, ideally having about 32gb of free space when i put the 64gb card into my phone. I cant seem to get this to work right for some reason.

I took the filled up 32gb card out of my phone put it into the adapter it came with and then put that into the sd card reader thats built into my windows 8 laptop. Copied the entire card to my desktop and it turns out to be 37gb worth of data some how?? The 32gb card is using fat32 and the new 64gb card is using exfat...not sure if that matters in any of this? Then I copied that entire folder to the blank 64gb card and windows is telling me i only have 15gb of free space left on the card. The 64gb card seems to read in windows as only about 60gb btw. Where my extra 4gb? regardless...even 60gb minus the 37gb copied to the card should give me at LEAST 23gb....not 15gb. So not sure whats going on here??

THEN i formatted the 64gb card again using NTFS, added back all the copied files from my 32gb and it said i had about 20gb of space left. I suppose thats better but still not what im looking for and i read that i shouldnt really be using NTFS anyways. So then I tried formatting the card in my phone with TWRP and same thing happened as before, only showing 15gb of free space with the exfat format. I noticed in the windows format utility i can chose an Allocation Unit Size...I had left it at the default...not sure if I should be changing that to one of the larger numbers?

Anyway, I just want to transfer my 32gb card to the new 64 gb card and have about 32gb of free space on there....any help with this would be great, thanks!
6th July 2014, 07:34 PM |#2  
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It depends on a few things. First is the average size of the files to be stored and retrieved. Also the number of files to be stored and retrieved. A single file may be stored in several segments. The last segment will probably not be full, hence wasted space that cannot be allocated. Smaller segments would result in less wasted space, but more segments per file. Larger segments would yield less segments per file but more waste.

All the segments are tracked by the FAT (file allocation table). This index keeps track of all the segments on your storage device. A smaller allocation unit size (segment) would yield in a larger FAT. This will also slow down your read/write speeds. The reverse is also true.

*It has been awhile since I had studied this stuff so my FAT might be a little randomized.
7th July 2014, 03:09 AM |#3  
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I'm not sure what you go going on.

Couple of quick comments. Not possible to have more data on the card than it's capable of holding; ie 37GB of data on a 32GB card. You may have some compressed files of something, but the compressed files are still a certain size until uncompressed. So, something may have gotten messed up. It happens.

As for your new card having less than 64GB of data, that is normal and expected. There is always some space lost for file allocation tables and various other stuff needed for devices to connect to the card.

As for the new card, since it blank, best thing to do, format using your phone. It's the best place to do it. It will guarantee it'll be formatted in a way that the phone is guaranteed to read and write. And it doesn't take that long; five minutes at the most in my experience, and usually it's more around two. If your computer can read and see the formatted card, I would than just copy/cut the files over to the phone that way, and not use the card reader that came with it. It does take a lot more time, but other than corrupted files, it's always works.

If fact, I almost never use those card readers. When I get a new card or phone and need to transfer data, I just connect it the computer, transfer files over to the computer that way. Format the phone storage or new microSD card (in the phone), than transfer from the computer to the new phone or microSD. Other than a file here and there, no issues. And of those few files, it usually turns out the file got corrupted because I won't be able to open on the PC, phone, or anywhere else. And the problem files are found when transferring from the phone to the PC. The biggest knock on this method, it can be very time consuming, especially if there are bad files.

Other thoughts, I don't recall Android being a NTFS friendly. I thought it was just FAT or exFAT (I believe this is what it generally uses). FAT32 is the arguably the cross platform friendliest since Windows, OSX, Linus, and so forth and all read and write to it. It does have a 4GB file limitation, which depending on what you're using, can be a big problem, especially with video files. I don't recall exFAT file size limit, but it's more than 4GB.
26th July 2014, 10:17 PM |#4  
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Thanks so much for the info guys! For whatever weird reason it seems the exta gigs of data that transferred off the sdcard was actually files i had deleted a while back...not sure why they were still on there but my phone was reading them as deleted. Not sure why they would copy back to the computer though when i never even saw them to select.
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