Why is the lvm volume not fully writable?

Question

linux

I created an lvm volume, created an ext4 FS there, and mounted it.
df -h shows that only 47G is available , even though all 52M is occupied .

/dev/mapper/backup 50G 52M 47G 1% /home/user/lv-backup

What is it connected with?

Answer 1

When creating ext4, 5% free space is reserved by default to solve fragmentation problems. You can change this setting with the command tune2fs -m N <устройство>, where N is the number of %.
https://unix.stackexchange.com/questions/7950/rese... - Details.
Don't forget about converting bytes to kilo/mega/gigabytes. In some cases, they count at the "rate" of 1024, and in some - 1000.