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Thread: thumb drives

  1. #1
    The Beast Master TZ Veteran PIPER's Avatar
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    thumb drives

    if ever the problem shows up......

    Q: I've been copying my Excel files to a dedicated USB thumb drive for backup for the past year. Suddenly, newly created Excel files will not copy. Certain other files that already are on that thumb drive will allow themselves to be overwritten, and the drive shows that it has plenty of room (it's less than half full, and the files are very small in relation to the available space). The Device Manager shows no errors with the drive. The problem is not limited to Excel files. I get an error message "Cannot copy [file name]; the directory or file cannot be created." I inserted a different thumb drive in a different USB port and the problem files copied to it fine. I am puzzled. Can you tell me what might be going on? —Tom Chero

    A: You say "the files are very small in relation to the available space"—that's a clue. Thumb drives use a variation on the old FAT (File Allocation Table) file system that was used in MS-DOS. A FAT-formatted drive has a fixed-size root directory. No matter how much space is available, if you fill up the root directory, you can't create any more files. And of course this is more likely to happen if the files are very small because you can pack more of them into the drive. Recopying an existing file is no problem, because it already has a directory entry. If the files have long filenames (any filename over eight characters, or that contains certain characters, such as a space), then they take two or more "slots" in the root directory and hence it gets used up faster.

    The solution is simple. Although the root directory's size is fixed, subdirectories can grow to hold as many directory entries as needed. So create a subfolder on your USB drive (you will probably have to move one or more files temporarily off the drive to do this). Now copy any new files into the subfolder. Solved!

  2. #2
    Old and Cranky Super Moderator rik's Avatar
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    Good Info PIPER!

  3. #3
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    Well he sort of got it right, fat 16 will limit ya like that. Though most pen drives are formatted with exfat or fat32, which doesn't have any limitations. So if ya run into this problem just back up your data real quick, and then repartition your drive to something not so 80 ish and go from there without worries.

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    Succeded in braking Windo TZ Veteran Dehcbad25's Avatar
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    o....format in ntfs. That is what I do

  5. #5
    Old and Cranky Super Moderator rik's Avatar
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    Quote Originally Posted by thraxed View Post
    exfat or fat32, which doesn't have any limitations.
    Limitations of FAT32 File System http://support.microsoft.com/kb/184006

    The following limitations exist using the FAT32 file system with Windows operating systems:

    * Clusters cannot be 64 kilobytes (KB) or larger. If clusters were 64 KB or larger, some programs (such as Setup programs) might calculate disk space incorrectly.

    * A volume must contain at least 65,527 clusters to use the FAT32 file system. You cannot increase the cluster size on a volume using the FAT32 file system so that it ends up with less than 65,527 clusters.

    * The maximum possible number of clusters on a volume using the FAT32 file system is 268,435,445. With a maximum of 32 KB per cluster with space for the file allocation table (FAT), this equates to a maximum disk size of approximately 8 terabytes (TB).

    * The ScanDisk tool included with Microsoft Windows 95 and Microsoft Windows 98 is a 16-bit program. Such programs have a single memory block maximum allocation size of 16 MB less 64 KB. Therefore, The Windows 95 or Windows 98 ScanDisk tool cannot process volumes using the FAT32 file system that have a FAT larger than 16 MB less 64 KB in size. A FAT entry on a volume using the FAT32 file system uses 4 bytes, so ScanDisk cannot process the FAT on a volume using the FAT32 file system that defines more than 4,177,920 clusters (including the two reserved clusters). Including the FATs themselves, this works out, at the maximum of 32 KB per cluster, to a volume size of 127.53 gigabytes (GB).

    * You cannot decrease the cluster size on a volume using the FAT32 file system so that the FAT ends up larger than 16 MB less 64 KB in size.

    * You cannot format a volume larger than 32 GB in size using the FAT32 file system in Windows 2000. The Windows 2000 FastFAT driver can mount and support volumes larger than 32 GB that use the FAT32 file system (subject to the other limits), but you cannot create one using the Format tool. This behavior is by design. If you need to create a volume larger than 32 GB, use the NTFS file system instead.

    Or there is this article: Limitations of the FAT32 File System in Windows XP

    http://support.microsoft.com/kb/314463

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