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Properties shows different sizes of folders and different numbers of folders and files in copy and original

Anonymous
2010-08-10T22:30:19+00:00

I used drag and drop to copy files from my computer's hard drive to two WD 1 Ter My Book external hard drives and on 1/2 ter external Passport. I tried to use properties to check if all files were copied correctly; however, the number of folders and sizes of the folders in the copied batch varied. The two 1 Ter hard drives had the same properties but this did not match the properties of the original or the copy on Passport. Properties showed inconsistencies in the first six files of the batch (of 15) between the original and the Passport although comparing the number and names of the files in each pair of folders showed no inconsistency. Since the copies are back-ups, I need to know how to confirm the copies are accurate, and if they are, I'd like to know why Properties doesn't show this.

Windows for home | Previous Windows versions | Files, folders, and storage

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  1. Anonymous
    2016-03-14T21:15:33+00:00

    The discrepancy in file count and therefore total folder size are most probably related to Windows Explorer limitation to handle large paths (long file names + long folder and subfolder names).

    Only reliable choice is robocopy or some third party tool that overcomes that limitation.

    As a diagnostic measure, you can use the subst command for both source and target paths. Then run DIR /S on both subst'ed paths and see if file and folder count, and size, match. Still totals may be LESS than those reported by a more powerfull tool which can better handle large paths.

    Good luck.

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  2. LemP 74,930 Reputation points Volunteer Moderator
    2010-08-11T00:46:34+00:00

    It's not clear if the discrepancies you see are only in the file sizes reported or something else. 

    When you say that there are "different numbers of folders and files" do you mean that some files and/or folders did not get copied, that some extraneous files and/or folders appeared in the copy destination,  or something else?

    If you're copying using drag-n-drop, you may get extra copies. This is caused by a shaky hand and/or a too-sensitive mouse.

    If you are seeing different file sizes for the same file(s), make sure that you're looking at the actual file size and not the "size on disk."  These two numbers are almost always different because Windows allocates disk space using "file allocation units" or clusters. 

    In Windows XP, the default file allocation size for partitions larger than 2 GB (which should include almost every hard drive today) is 4KB, but this size can be set to a smaller value when the partition is formatted.  If a drive originally was formatted using the FAT file system and then CONVERTed into NTFS, Windows may have set the file allocation size of the converted partition to only 512 bytes.  For more info, seeKB314878 and Converting FAT32 to NTFS in Windows XP .  If the cluster size on the source drive is different from the cluster size on the destination size, the "size on disk" for the same data could well be different.

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