1.8 Explain common features and tools of the macOS/desktop operating system
📘CompTIA A+ Core 2 (220-1202)
What is Disk Utility?
Disk Utility is a built-in macOS tool used to manage storage devices.
It allows technicians to view, format, repair, partition, and erase disks on a Mac.
In an IT environment, Disk Utility is commonly used for:
- Preparing new storage devices
- Fixing disk errors
- Managing partitions
- Checking disk health
- Securely erasing data
Disk Utility works with:
- Internal hard drives (HDD)
- Internal solid-state drives (SSD)
- External USB drives
- External hard drives
- Disk images (.dmg files)
How to Access Disk Utility
Disk Utility can be opened in multiple ways:
- Applications → Utilities → Disk Utility
- Using Spotlight Search (Command + Space → type Disk Utility)
- From macOS Recovery Mode (used when the system does not boot)
Exam Tip: Knowing where Disk Utility is located is important for troubleshooting questions.
Disk Utility Interface Overview
When Disk Utility opens, it shows:
- Sidebar – Lists all disks and volumes
- Toolbar – Contains common disk management actions
- Main window – Displays information about the selected disk
Show All Devices
By default, macOS may only show volumes.
Selecting “Show All Devices” allows technicians to see:
- Physical disks
- Containers
- Volumes
Exam Tip: Always enable Show All Devices when managing partitions or repairing disks.
Key Features of Disk Utility (Exam Critical)
1. Disk First Aid
What is Disk First Aid?
Disk First Aid is a tool that:
- Checks disks for file system errors
- Repairs logical disk issues
- Verifies disk structure and permissions
What It Can Fix:
- Corrupted file system structures
- Directory errors
- Permission problems
What It Cannot Fix:
- Physical hardware damage
- Completely failed drives
When IT Staff Use It:
- System crashes
- Apps fail to open
- Disk becomes read-only
- macOS shows disk error messages
Exam Tip:
Disk First Aid is the primary macOS disk repair tool.
2. Erase (Formatting Disks)
What Does Erase Do?
The Erase option:
- Deletes all data on a disk or volume
- Creates a new file system
- Prepares disks for reuse
Common File System Formats (Important for Exam)
APFS (Apple File System)
- Default for modern macOS
- Optimized for SSDs
- Supports encryption and snapshots
Mac OS Extended (HFS+)
- Used by older versions of macOS
- Less efficient than APFS
ExFAT
- Compatible with macOS and Windows
- Used for external drives
FAT32
- Older format
- Limited file size support
Exam Tip:
APFS is the default and recommended file system for newer macOS versions.
3. Partitioning Disks
What Is Partitioning?
Partitioning divides a single physical disk into multiple logical sections, each appearing as a separate volume.
Why Partition Disks?
- Separate operating systems and data
- Organize storage
- Apply different file systems
Partition Tools in Disk Utility:
- Add or remove partitions
- Resize partitions
- Assign file systems
Exam Tip:
Partitioning is done before installing operating systems or for advanced storage management.
4. Mount and Unmount Volumes
Mounting a Disk
- Makes the disk available to the operating system
- Allows files to be accessed
Unmounting a Disk
- Safely disconnects the disk
- Prevents data corruption
Why This Matters in IT:
- Required before removing external drives
- Needed before running some repair tasks
Exam Tip:
Always unmount disks before removal to avoid data loss.
5. Disk Images (.dmg Files)
What Is a Disk Image?
A disk image (.dmg) is a file that behaves like a virtual disk.
Disk Utility Can:
- Open disk images
- Create disk images
- Convert disk images
- Verify disk images
Common Uses:
- Software distribution
- System backups
- Software installation packages
Exam Tip:
macOS commonly uses .dmg files for application installation.
6. Disk Information and Health Monitoring
Disk Utility shows detailed information such as:
- Disk capacity
- Available space
- File system type
- Partition scheme (GUID Partition Map)
- SMART status (for supported drives)
SMART Status
- Indicates basic disk health
- Shows whether a disk is likely to fail
Exam Tip:
Disk Utility can view disk health, but it is not advanced diagnostic software.
7. Security and Data Protection
Secure Erase (Limited on SSDs)
- Overwrites data to prevent recovery
- More effective on HDDs than SSDs
Encryption Support
- APFS supports full-disk encryption
- Works with FileVault
Exam Tip:
Modern SSDs handle data deletion differently, so secure erase options may be limited.
Disk Utility in macOS Recovery Mode
Disk Utility is especially important when:
- macOS fails to boot
- Startup disk is corrupted
- OS needs to be reinstalled
In Recovery Mode, Disk Utility can:
- Repair startup disks
- Erase disks
- Prepare disks for OS reinstallation
Exam Tip:
Disk Utility is a key troubleshooting tool when macOS does not start.
Common Disk Utility Tasks (Exam Scenarios)
You may be asked which tool to use when:
- A disk shows errors → Disk First Aid
- Preparing a new drive → Erase
- Dividing storage → Partition
- Checking disk format → Disk Information
- Opening installer files → Disk Images (.dmg)
Key Exam Takeaways (Must Remember)
- Disk Utility is the main disk management tool in macOS
- Disk First Aid is used to verify and repair disks
- APFS is the default macOS file system
- Disk Utility can erase, partition, mount, and repair disks
- Used heavily in macOS Recovery Mode
- Supports both internal and external storage devices
