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"Size on disk" is much larger than actual size

Anonymous
2023-05-14T15:38:27+00:00

Hello,

So I have this 4TB external SSD that I formatted with exFAT so that it could be compatible with any computer I plug it into.

The problem is that most of the files I put on the drive take up much more space on the drive than it should.

The "Size on disk" is so much larger than the actual size. It's a new drive, and I only have a few hundred GB worth of stuff in there, so it's probably not noticeable, but I'm worried that this wasted space will add up over time as I fill it up more.

Is this a flaw with exFAT? In which case, will formatting it to NTFS be better?

Here's a screenshot of what I'm talking about:

Windows for home | Windows 10 | Files, folders, and storage

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  1. DaveM121 872.1K Reputation points Independent Advisor
    2023-05-14T16:17:35+00:00

    Hi NelsonXT,

    I am Dave, I will help you with this.

    This is caused by the Cluster size (allocation unit size) set on the disk, I always find the default NTFS settings to be the most efficient,

    As a basic understanding, if the cluster size is set to 1MB and a file is 1.1MB in size, it will use 2MB or 2 clusters, because it cannot fit in 1 cluster, that is why 'Size on Disk' will be larger than actual file size.

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  2. DaveM121 872.1K Reputation points Independent Advisor
    2023-05-14T16:42:05+00:00

    Hi NelsonXT,

    That is true, NTFS is not natively supported on a Mac, you would need 3rd party drivers.

    No matter what file system you select, Size on Disk will always be bigger than actual file size, unless the size of the file is nearly divisible by the cluster size.

    If you will be using that drive to store files from a Mac as well as a PC, then stay with the ExFAT format.

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  3. Anonymous
    2023-05-14T16:35:27+00:00

    Thanks.

    So in this case, will switching to NTFS be better than staying on exFAT?

    I think the smallest cluster size for exFAT is 256KB, while for NTFS, it's like 512 bytes (correct me if I'm wrong).

    The only downside I know of, is that I won't be able to put files on it if I'm on like a macbook (as an example).

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  4. Igor Leyko 110.6K Reputation points Independent Advisor
    2023-05-14T16:50:55+00:00

    Just a small clarification. The best cluster size for NTFS is 4 KB mostly.

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