ACSP File System and Storage 2

Question 1

In APFS, what is a 'volume group' and how does it relate to the macOS system and data volumes?

Accepted Answer

A volume group contains multiple APFS volumes that share the same storage pool, including the sealed read-only System volume and a writable Data volume

Answer

In macOS, the APFS volume group contains at least two volumes sharing the same APFS container: a read-only, cryptographically sealed System volume (macOS files) and a writable Data volume (user data and apps). They appear as one disk in Finder.

Question 2

What is a 'firmlink' in APFS and how does it differ from a symbolic link?

Accepted Answer

A firmlink is a bi-directional, file-system-level hard link between two volumes that behaves like a directory, while a symlink is a one-directional pointer to a path

Answer

Firmlinks are a new APFS link type that creates a true bi-directional, kernel-level tunnel between paths on different volumes (like System and Data volumes), making them appear as a single path. Unlike symlinks, they are fully transparent to applications and cannot be easily broken.

Question 3

What does APFS 'space sharing' mean in the context of disk management?

Accepted Answer

Multiple APFS volumes in the same container share the total available space, with no fixed partition sizes assigned to individual volumes

Answer

APFS space sharing means all volumes within an APFS container draw from the same shared pool of free space. No fixed size is allocated to each volume — they all grow and shrink dynamically, eliminating the partition size planning problem.

Question 4

Which Disk Utility operation should be used when a volume shows errors in the First Aid check?

Accepted Answer

Run First Aid again after booting from macOS Recovery or an external startup disk

Answer

When First Aid reports errors that cannot be repaired on a mounted boot volume, the correct approach is to boot from macOS Recovery or an external startup disk and run First Aid from there, since a volume cannot fully repair itself while it is mounted and in use.

Question 5

What is the purpose of the 'Signed System Volume' (SSV) in Apple silicon and T2 Macs?

Accepted Answer

It cryptographically seals the macOS system files so any unauthorized modification is detected at boot and the system refuses to start

Answer

The Signed System Volume (SSV) creates a cryptographic hash tree (Merkle tree) of all macOS system files. At boot, the kernel verifies this seal — if any system file has been modified or tampered with, the Mac detects the mismatch and refuses to boot from that volume.

ACSP - Apple Certified Support Professional Practice Test

ACSP - Apple Certified Support Professional Practice Test

ACSP File System and Storage 2