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  1. #1

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    Default Formatting a USB drive for Mac & Windows

    This problem has been annoying me for a while so thought I'd put it out there. When I format a 4GB USB stick as MS-DOS (FAT) in Disk Utility, then plug it into a windows machine I get the error.

    "Disk in drive E is not formatted. Do you want to format it now?"

    Ok, so fine, I'll use Windows to format the drive instead. But then Windows only gives me the option to select 200MB under the capacity drop down.

    I have had this same issue with various USB drives. Isn't Disk Utility MS-DOS (FAT32) meant to work in Windows? Is there another app I can use to format the drive?

  2. #2
    arkenstone's Avatar arkenstone is offline Pinball Wizard

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    Is it possible your thumbdrive has two parititons on it?

    Some of them have a small partition for their own software - say 200 meg out of 16 gig or something. Is it possible that's what you're seeing?

    When you view it in Disk Utility (Mac) or Disk Management (Windows) what do you see?

    Windows will give you an artificial limitation of 127Gig for a FAT32 partititon but the file system itself supports up to around 2TB from memory. Just don't use explorer to format it (use either your Mac or a third party tool for Windows)
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  3. #3
    Brains's Avatar Brains is offline Still stuck in 1984

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    Sounds like the USB drive has two partitions on it, the first one is 200 MB because Disk Utility wanted to put the EFI loader on there at some stage ... and Windows has absolutely no idea how to deal with it because it is Apple-specific.

    Try this: plug the USB drive into your Windows machine, open Disk Management (either right-click your 'My Computer' icon and choose 'Manage' or go into Administrative Tools and select 'Computer Management'). Scroll the list to see the partition arrangement for your USB drive. If there is more than one partition, delete both partitions then make a new one that fills the entire drive.

  4. #4

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    Sounds to me like you formatted the drive as GPT, which puts a 200MB EFI partition onto the first section of the disk.

    You should reformat it as MBR with a single FAT32 partition. GPT is not compatible with Win XP and below.

  5. #5
    The_Hawk's Avatar The_Hawk is offline Subtle plans are here again!

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    I have somehow managed to format a full disk to "MS-DOS (Fat)" and not have it readable on a windows PC a couple of times (no clue how) since I was formatting from NTFS to Fat and didn't change the number of partitions or anything.

    In most cases I just format my memory sticks when in boot camp or on the work PC and delete files from there... seems to have less issues. I assume there is something I'm doing wrong, but I format memory sticks so infrequenty that I haven't worked out what yet.
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  6. #6

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    Default

    I have the same problem! Please help me!!

    I tried what you guys recommended with Disk Management (I also have a Windows 7 Computer) and you guys were right about there being 2 partitions.

    The problem is though that Disk Management wont let me delete the volume to make 1 partion or let me format the partion either. The 200 MB partion will let me format it but the other 3.58 GB partion gives me "An unexpected error has occurred. Check the System Event Log for more information on the error. Close the Disk Management console, then restart Disk Management or restart the computer." And it keeps popping up no matter how many times I restart or re-try to format/delete the volume.


    Let me know what the best route is.


    THANKS!!!

  7. #7
    Geoff3DMN's Avatar Geoff3DMN is offline Motorbikes - lazy mans Zen

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    I loaned a USB stick to one of the guys at work and it came back with this problem.

    I have been unable to get any of the utilities on either my OS X machine or my windows machine to re partition the USB stick into 1 partition in a way that is readable on both OS's
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  8. #8
    gikku is offline

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    I spent 3 hours last night trying to overcome this very issue.
    In the end I gave up on the Windows 7 box and went back to the Mac.
    Life's all good again.
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  9. #9

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    Quote Originally Posted by Geoff3DMN View Post
    I loaned a USB stick to one of the guys at work and it came back with this problem.

    I have been unable to get any of the utilities on either my OS X machine or my windows machine to re partition the USB stick into 1 partition in a way that is readable on both OS's
    Exactly the same here,

    dammit I lost a Lacie imakey

  10. #10
    The_Hawk's Avatar The_Hawk is offline Subtle plans are here again!

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    Default Re: Formatting a USB drive for Mac & Windows

    Brain flash...
    They don't happen to be San Disk memory sticks do they??
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  11. #11
    Geoff3DMN's Avatar Geoff3DMN is offline Motorbikes - lazy mans Zen

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    Quote Originally Posted by The_Hawk View Post
    Brain flash...
    They don't happen to be San Disk memory sticks do they??
    Mine is a San Disk Cruzer yes. How is that relevant?
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  12. #12
    The_Hawk's Avatar The_Hawk is offline Subtle plans are here again!

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    The SanDisk Cruiser uses U3 software which can encrypt the memory stick. We had a bunch of them at work (Windows XP) and had nothing but problems, although from memory it was more about the Novel setup than it was about the memory sticks. In short inserting the memory stick would load a virtual CD sort of thing then install it's own software.

    Long story short, removing the U3 crap solved all problems and the memory stick then worked like a normal memory stick again

    It's supposed to be a Windows only thing, I have never had a Cruiser on a Mac before "fixing" it.

    Try this link for details: Removing U3 Launchpad on a PC
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  13. #13

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    Default Formatting a USB drive for Mac & Windows on a Mac

    I have managed to do it using Disk Utility.

    • Select the drive, then go to the partition section.
    • Select the format as MS-DOS (FAT) (it will make this FAT32).
    • Select the number of partitions (I have always selected one) in the drop-down box.
    • Click on the Options button at the bottom of the partition diagram.
    • Select the Master Boot Record option.


    If you now apply that, it should create the drive using MBR (master boot record) rather than GUID Partition Table (GPT). Windows is incapable of reading GPT when created on a Mac. If you don't select an option, it seems to use GPT as the default, thereby rendering the drive unreadable on a Windows machine.

  14. #14
    iTy
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    Quote Originally Posted by The_Hawk View Post

    Long story short, removing the U3 crap solved all problems and the memory stick then worked like a normal memory stick again

    It's supposed to be a Windows only thing, I have never had a Cruiser on a Mac before "fixing" it.

    Try this link for details: Removing U3 Launchpad on a PC
    That's exactly what I did with my Sandisk. THat U3 crap tried to install itself everytime.

    Though, the partition containing the software never really disappears.

    When I stick in a Windows machine, the Disc comes up briefly before it disappears again.

    I have another disk 50% partitioned as HFS and the other Fat32. My Win 7 machines have no problem reading both partitions. Does Win 7 support HFS now?

  15. #15

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    Win7 doesn't support HFS+, but it does support GPT disks and the Boot Camp drivers that came with 10.6 include a HFS driver.

  16. #16

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    Smile Oceanic. Thankyou!

    Oceanic,

    Whoever you are, your simple approach and solution to this problem has just ended about 6 months of research and testing and painstaking crapping around on this issue at my end. I knew this would be the case, I just couldn't find it.

    Currently deploying a project on USB sticks and these GPT related errors are just a nightmare, and scarcely documented.

    From the amount of reading I've done on this topic, your suggested solution is by far the simplest, cost effective and reliable way to solve this problem.

    It's also great to have been able to solve the issue so swiftly in Disk Utility in OSX, without using yet another downloadable piece of PC junk.

    Every single one of those supposed 'launcher' or 'security partition' style apps I downloaded for both Sandisk, Vertbatim USB drives was either incompatible with the range of sticks i'm testing on, or had some other issue that didn't work. Virtually NONE of them had a mac version available. If they did, the process was as cryptic as all get out.

    These companies making and selling these products really need to sort this - they're certainly moving a few of these units these days and must be making ALMOST enough money to pay someone for the 36 minutes it would probably take to put a help guide on a website.....

    For Apple (if you're listening guys...), it would be useful to have a more visible set of options + explanations in disk utility so you know that your 'erase' function is just about to create the GPT on the disk. It's a fairly well documented problem.

    Given that the main reason that you'd be formatting using MS-DOS in Disk Utility is to create a cross platform volume, a GPT result on XP is hardly an ideal outcome from a standard format routine. For the unknowing user, deathtrap.

    I realise it probably doesn't crop up that much, but it's a fundamental flaw that is WAY too easy to solve once you know how. There's no reason why some simple help text such as oceanic's shouldn't be available for mac users everywhere it counts.

    Thank you. Thank you. Thank you.

    Do you get it? I'm pretty relieved.

    ( BTW: The extra step i had to do was reformat the MBR enabled stick in XP in order for it to display again on mac as a regular fat32 volume.)



    Quote Originally Posted by oceanic View Post
    I have managed to do it using Disk Utility.

    • Select the drive, then go to the partition section.
    • Select the format as MS-DOS (FAT) (it will make this FAT32).
    • Select the number of partitions (I have always selected one) in the drop-down box.
    • Click on the Options button at the bottom of the partition diagram.
    • Select the Master Boot Record option.


    If you now apply that, it should create the drive using MBR (master boot record) rather than GUID Partition Table (GPT). Windows is incapable of reading GPT when created on a Mac. If you don't select an option, it seems to use GPT as the default, thereby rendering the drive unreadable on a Windows machine.

  17. #17

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    Default YEAHHH

    The disk utility thing....what oceanic told us bout it really worked for me. At first i was trying to erase all partitions but the fact is that you have to choose to stay with one partition and then format it with the MAster Boot, otherwise it will automatically choose GUID

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