File System and Storage Flashcards
6 cards from real ACSP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 File System and Storage flashcards as text
In APFS, what is a 'volume group' and how does it relate to the macOS system and data volumes?
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
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.
What is a 'firmlink' in APFS and how does it differ from a symbolic link?
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
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.
What does APFS 'space sharing' mean in the context of disk management?
Answer: Multiple APFS volumes in the same container share the total available space, with no fixed partition sizes assigned to individual volumes
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.
Which Disk Utility operation should be used when a volume shows errors in the First Aid check?
Answer: Run First Aid again after booting from macOS Recovery or an external startup disk
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.
What is the purpose of the 'Signed System Volume' (SSV) in Apple silicon and T2 Macs?
Answer: It cryptographically seals the macOS system files so any unauthorized modification is detected at boot and the system refuses to start
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.
What storage interface do all Apple silicon Macs use for their internal SSD?
Answer: NVMe over a custom Apple fabric integrated directly with the SoC
Apple silicon Macs use NVMe storage connected through Apple's custom die-to-die fabric (the same substrate as the SoC), providing extremely fast storage access. The NAND flash is soldered directly to the logic board and shares the unified memory architecture.