Drive lost size after format

When this drive was in exFAT, it was 931,5 GB. After formatting to ext4 it’s only 915,8 GB, which are almost 20 GB lost. The way I formatted was sudo mkfs -t ext4 /dev/sda1. I know bytes can be counted deceitfully by manufacturers but this isn’t the case as the drive was 1 TB as opposed to the shown 931 GB, so there has been size loss.

The folder is completely empty and shows no file or folder at all. I don’t know about drives or what can cause it, but last time this happened was to some USB drive I burned an ISO on, which I haven’t to this big drive.

EDIT: This has nothing to do with reserved space. I mean the MAXIMUM listed space is still inferior. I forgot to clarify that I’ve already modified the reserved space and there is still size loss.

Please read the section on reserved blocks in EXT4 article in ArchWiki.

If what is described there corresponds to your use case then reformat and disable the reserved blocks.
Or adjust the percentage reserved.

Ext4 reserves 5% of the drive for root.

You can adjust using tune2fs

@pebcak @dalto no, this is not reserved space. It was even less space until I discovered that. But even after it, the total available data is still missing 20 GB.

Note that filesystems are different and consume disk space differently.

Try formatting it back to exFAT (or similar). Is it then still 931,5 GB?

The disk sizes can be announced with multiples of 1000 or 1024 bytes, which result in visible “differences”. Vendors typically want to use 1000 as a factor to show bigger GB numbers.

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Both of my 1tb externals show a total of 915.8
My 5 tb shows my capacity at 4.5

I don’t think you actually lost diskspace as much as @manuel just pointed out sizes vary by which byte factor is used.

I believe the system uses some space when you format and partition. This is the file system table and yes it does take up some space the rest is again how they factor the bytes

I would expect vfat to use 1000 and ext4 1024 so that would be you “loss”

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Makes sense, but I need to do another question.

What you say matches what I’ve seen, I formatted again to FAT32 and it shown 931,5. And then reformatted to ext4 and marked 915,8.

But, why? I already expected this when I bought the drive, from 1 TB to 931. What I don’t understand is why AGAIN to 915. In theory makers count GB in units of 1000, so when converted to 1024 I expect the loss, that should be it. What made it to be counted differently two times? Does ext4 has some count form I’m not aware of?

I have an SSD formatted to ext4 and it shows 931,5G of size with command

lsblk -fm

but size 916G with command

df -hT


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df -H should should show 931,5G.

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Actually it shows 984G ! :star_struck:

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