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Say I have a 1TB SSD and I want to create a 400GB partition with ext4.
So I use fdisk and mkfs to achieve that:

#### fdisk ####
sudo fdisk /dev/sdb

# New primary partition, with partition 1 starts with 2048 sector:
n
p
1
2048

# The last sector
+400G


#### Configure the file system ####
sudo mkfs -t ext4 /dev/sdb1
sudo tune2f -m 0 /dev/sdb1

It turns out that the size I saw in df is less than I expected:

# expected: 400 * 1024 * 1024 = 419430400
/dev/sdb1      411725224

So now I use +408G instead of +400G in fdisk to "achieve" what I want,
but obviously it was not the smartest solution.
I've also tried to use +419430400K instead of +400G in fdisk but the result is same.

Is there any formula to create a partition with the size I want?

Plus
  • 1
  • Does this answer your question? [disk space overhead in ext4](https://serverfault.com/questions/282317/disk-space-overhead-in-ext4) – John Mahowald Jun 12 '22 at 20:30

0 Answers0