Mirrored disk not identical

[vookman77]

Hello, I've been using Freefilesync to clone two individual external hard drives. I use the "Mirror" method where the contents of drive A are copied to drive B. These drives are identical (brand, model, and capacity) but drive B has about 400 gb of additional contents and I can't figure out why. I have checked the individual folders on both drives and they all match - same capacity and same number of files/folders. I have also emptied the recycle bin of drive B but I only managed to save about 30 gigabytes. The difference of 400 gigabytes still remains. Does anyone have any suggestions? Any help would be appreciated. Thanks.

[Plerry]

If disk B is formatted with a different (bigger) block-size, then data on B may occupy more disk capacity than on A. Even more so in case of a lot of small files.

[vookman77]

Thanks but the disks are both ntfs.

[xCSxXenon]

Run SpaceSniffer on them

[vookman77]

Yes that's it. It was the recycle bin in the drive. Problem solved. Thanks.