Lesson 26 - Troubleshoot Startup and System Issues Flashcards
What are the primary system initialization stages in macOS Sierra? What visual and audible cues do these stages provide?
Each primary stage of system startup can be indicated by the following cues:
• Firmware—A bright flash of the power-on light, followed by a light-gray screen on the primary display
• Start up—A dark-gray Apple logo on the primary display
• Kernel—A small, dark-gray spinning gear or spinning Earth icon below the Apple logo
• System launchd—A white screen on all displays followed by the login screen
What does the firmware do? What’s the Power-On Self-Test (POST)?
The firmware initializes the Mac computer’s hardware and locates the startup file on a system volume. The POST checks for basic hardware functionality when a Mac powers on.
What role does launchd serve during Mac startup?
launchd is responsible for starting macOS Sierra processes. It also manages macOS Sierra initialization and starts loginwindow.
Which items are automatically started by launchd during Mac start up?
During macOS Sierra start up, launchd starts these daemons and scripts:
• /System/ Library/LaunchDaemons
• /Library/LaunchDaemons
• /Library/StartupItems (through SystemStarter)
• /etc/rc.local UNIX script (if it exists)
What are the primary user session stages in macOS Sierra? What visual and audible cues do these stages provide?
Each primary stage of a user session can be indicated by the following signs:
• displays the login screen.
• launchd loads apps like the Finder after user authentication.
• The user environment is active any time a user logs in to macOS Sierra.
What’s the difference between launch daemons, startup items, launch agents, and login items?
The administrator account launchd process launches Launch daemons and startup items during Mac start up. User account launchd processes launch agents and login items during user environment startups.
What are Safe Sleep and Power Nap?
When a Mac battery drains, Safe Sleep saves the macOS Sierra state to permanent storage. Power Nap enables a Mac to automatically wake in low-power mode. This enables the Mac to perform app and macOS Sierra updates.
What happens during user logout?
During user logout, the user’s loginwindow process performs these actions:
• Requests that user apps quit.
• Automatically quits user background processes.
• Runs logout scripts.
• Records the logout to the main system.log file.
• Resets device permissions and preferences to their defaults.
• Quits the user’s loginwindow and launchd processes.
What happens during Mac shutdown?
When a Mac shuts down, loginwindow logs users out and then tells the kernel to quit the remaining macOS Sierra processes. Then the Mac shuts down.
Which keyboard shortcut is used to start up in safe mode?
Hold down the Shift key during startup to initiate safe mode.
Which keyboard shortcut can you temporarily use to choose another startup disk?
Hold down the Option key during startup to open Startup Manager. This enables you to temporarily choose another startup disk.
Which changes are made when macOS Sierra starts up in safe mode?
Startup in safe mode performs the following permanent actions:
• Attempts to repair the system volume structure
• Deletes system third-party kernel extension (KEXT) caches
• Deletes font caches
Which items aren’t loaded when macOS Sierra starts up in safe mode?
When macOS Sierra performs a startup in safe mode, it doesn’t load KEXTs, third-party launch agents, third- party launch daemons, third-party startup items, third-party fonts, any user login items, or any user-specific launch agents.
How do you resolve an issue that disappears when a Mac successfully starts up in safe mode?
If an issue disappears when a startup in safe mode is successful, remove the third-party startup resource that caused the issue. The best way to isolate the issue is to start up the Mac in Verbose mode and observe where the startup process fails. Hold down command-V to start Verbose mode.
