Linux – Iptables / What is the difference between connmark and mark

Halting involves stopping all CPUs on the system. Powering off involves sending an ACPI command to signal the PSU to disconnect main power.

This is called slack space:

Each layer of abstraction on top of individual bits and bytes results in wasted space when a datafile is smaller than the smallest data unit the file system is capable of tracking. This wasted space within a sector, cluster, or block is commonly referred to as slack space, and it cannot normally be used for storage of additional data. For individual 256-byte sectors, the maximum wasted space is 255 bytes. For 64 kilobyte clusters, the maximum wasted space is 65,535 bytes.

So, if your filesystem allocates space in units of 64 KB, and you store a 3 KB file, then:

• the file's actual size is 3 KB.
• the file's resident size is 64 KB, as the remaining 61 KB in that unit can't be allocated to another file and is thus lost.

Note: Some filesystems support block suballocation, which helps to mitigate this issue by assigning multiple small files (or the tail ends of large files) into the same block.