Significant size difference between Mirrored 8TB exFAT drives?

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Posts: 2
Joined: 8 Jan 2026

dr.angelo

Hi.

After MIRROR operation, Linux DISKS GUI shows the source drive as 52.2% full and the mirrored drive, 74.4% full. FFS Comparison shows the destination drive with = in both Action and Difference views. And a quick visual comparison of each drive's folders looks like they are identical. Both drives are formatted exFAT.

Q: Can you think of a reason for the significant difference in the data size?

(Apologies if this is a dumb question... i am a Noob. ;0)

Thank You, Friend
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Posts: 4867
Joined: 11 Jun 2019

xCSxXenon

https://freefilesync.org/faq.php#explorer-mismatch
You can also use a disk space analyzer to get more detailed information. I use WizTree on Windows and it shows size and space on disk, which is probably where your mismatch is. What are the sector sizes for each drive?