Spazio occupato /3

Lo spazio a volte NON è allocato se non necessario:

root@linuxday2022:/mnt# for i in $(seq 1 999999999); do echo “Breve prologo”; done > test3

root@linuxday2022:/mnt# df -k .

File system 1K-blocchi Usati Disponib. Uso% Montato su

/dev/vdb1 104805380 18336732 86468648 18% /mnt

root@linuxday2022:/mnt# ls -l test3

-rw-r--r-- 1 root root 17996400180 22 ott 01.23 test3

root@linuxday2022:/mnt# cp --reflink test3 test3-copia

root@linuxday2022:/mnt# ls -l

totale 35149324

-rw-r--r-- 1 root root 17996400180 22 ott 01.23 test3

-rw-r--r-- 1 root root 17996400180 22 ott 01.25 test3-copia

root@linuxday2022:/mnt# du -sk *

17574708 test3

17574616 test3-copia

root@linuxday2022:/mnt# df -k .

File system 1K-blocchi Usati Disponib. Uso% Montato su

/dev/vdb1 104805380 18336736 86468644 18% /mnt

root@linuxday2022:/mnt# dd if=/dev/zero of=test3 conv=notrunc bs=512 count=10000

10000+0 records in

10000+0 records out

5120000 bytes (5,1 MB, 4,9 MiB) copied, 0,121072 s, 42,3 MB/s

root@linuxday2022:/mnt# df -k .

File system 1K-blocchi Usati Disponib. Uso% Montato su

/dev/vdb1 104805380 18341800 86463580 18% /mnt

Dai file ai blocchi del disco

Copy on write!