External Hard Drives: 'Size' VS 'Size on Disk' Question

Hello there, and thank you for viewing my thread!

After formatting my PC, I have made a fresh back up of all of my data onto my external hard drive (as you do). The problem I have, is that the external hard drive is showing as pretty much full, but there's nowhere near that much data on it!

I did a little bit of digging, and noticed that when I right click a folder on the external hard drive and go to 'Properties' that the size of the file shows as one value and the size on disk value is significantly larger in most cases.

In some cases, both values do not reflect the actual size of the file on my desktop.

The ExHD is in ExFat format, and I'm assuming it's something to do with the way it's formatted, I just don't know how to fix it. I've tried it a couple of different ways, with different 'Allocation Unit Size's, but for how long it takes to complete the back-up's each time I'd rather just ask for help and find out where I'm going wrong.

If anyone could help me sort this out I'd really appreciate it.

I edit a lot of home movies of my daughter, some video files are as large as 10GB so I cannot use the 4GB file size maximum given by NTFS.

Thank you so much!

Megahertz07 said:

Data is stored on disk on small pieces called clusters.
A cluster can't be shared by two files. For example, if you have a cluster size of 1M and you storing a 2.1M, it will take 3 clusters, 2 of them full and one with 0.1M. The remaining 0.9 will be empty. In this case you have a 2.1M of data but it takes 3M on disk.
The smallest clusters are, the more efficient disk is.

My suggestion is, unless you use the external disk on a Mac computer, format it as NTFS.
On disk manager, delete all external disk partitions, create new, format as NTFS. Default cluster size is 4k.
What Should I Set the Allocation Unit Size to When Formatting?

Thanks for replying, like I said before I cannot use NTFS because I can't put my larger files on it due to the 4GB maximum file size it allows.

I have files as large as 41GB on NTFS drives proving your info that NTFS has a maximum size of only 4GB is wrong. Almost no Windows users use anything other than NTFS for HDDs and SSDs.

You need to make sure the data on the laptop is intact, then reformat the external drive, using all the default settings. to reformat, just go to Computer in the Start Menu, right click on the drive, click on Format, then follow the prompts. Use all of the default settings. You will essentially wipe all the data on the drive so you will have to backup the laptop again.