mirrored hdd uses less space than the original one. also there are less files on the mirrored one.

[blackthedot]

I have an archive of many many files on my drive N: which I, from time to time, mirror to my drive O: with freefile sync. works pretty well, but recently i noticed some inconsistencies. at first I noticed that O: is using less space than N:, even though both hdd's are the same size (even the same model). i then compared them in 'getFolderSize' which shows that neither their folders are the same size (almost though), nor are they containing the same amounts of files. to elaborate, i made a few screenshots:

https://dl.dropboxusercontent.com/u/21857535/perm/ffs1.png (blacked out some names for privacy reasons)

the problem is also there, when i use "content" as comparison method in ffs, even though it finds more differences then, than with the "size and date" comparison method.

thanks in advance to anyone who may shed some light on this matter.

thanks in advance for any info on this matter.

[Plerry]

There might be different, mutually non-exclusive reasons:
1)
File-size and disk-usage are two different things.
If the two disks are not formatted exactly identical (e.g block-size),
the disk-usage can be different, even if all files are identical.
2)
The difference in number of files might be due to filter settings.
You might want to check the Exclude filter for your mirror-sync.
Files matching your Exclude filter setting are ignored during the sync
and thus might cause differences in file-count.

[blackthedot]

There might be different, mutually non-exclusive reasons:
1)
File-size and disk-usage are two different things.
If the two disks are not formatted exactly identical (e.g block-size),
the disk-usage can be different, even if all files are identical.
2)
The difference in number of files might be due to filter settings.
You might want to check the Exclude filter for your mirror-sync.
Files matching your Exclude filter setting are ignored during the sync
and thus might cause differences in file-count.

hey, thanks for your answer. i did check with chkdsk, and both drives have the same cluster size (4k), both are NTFS.

i also, previous to my original post here, delete all the filters i had (there were only the default filters), except system volume info, and i still got quite different results :S.