In early versions of Windows, corrupted system files are one of the most common causes of startup failure. Windows Server 2012 R2 includes built-in diagnostics to automatically detect corrupted system files during startup and guide you through automated or manual recovery. To resolve startup problems, Windows Server 2012 R2 uses the Startup Repair tool (StR), which is installed automatically and started when a system fails to boot. Once started, StR attempts to determine the cause of the startup failure by analyzing startup logs and error reports. Then StR attempts to fix the problem automatically. If StR is unable to resolve the problem, it restores the system to the last known working state and then provides diagnostic information and support options for further troubleshooting.
Hardware problems addressed by built-in diagnostics include error detection and disk failure detection. If a device is having problems, hardware diagnostics can detect error conditions and either repair the problem automatically or guide the user through a recovery process. With disk drives, hardware diagnostics can use fault reports provided by disk drives to detect potential failures and alert you before they happen. Hardware diagnostics can also help guide you through the backup process after alerting you that a disk might be failing.
Performance problems addressed by built-in diagnostics include slow application startup, slow boot, slow standby/resume, and slow shutdown. If a computer is experiencing degraded performance, performance diagnostics can detect the problem and provide possible solutions for resolving the problem. For advanced performance issues, you can track related performance and reliability data in the Performance Diagnostics console, which includes a performance monitor and a reliability monitor.
Memory problems addressed by built-in diagnostics include both memory leaks and failing memory. A memory leak occurs if an application or a system component doesn’t completely free areas of physical memory after it is done with them. If you suspect that a computer has a memory problem that is not being automatically detected, you can run Windows Memory Diagnostics manually during startup by selecting the related option. If the Windows Memory Diagnostics option is not provided during startup, you can run the program by following these steps:
1. Start Windows Memory Diagnostics. One way to do this is to enter mdsched.exe in the App Search box, and then press Enter.
2. Choose whether to restart the computer now and run the tool immediately or schedule the tool to check for problems at the next restart.
3. Windows Memory Diagnostics runs automatically after the computer restarts, by using the standard test mix and performing two test passes by default.
You can change the run options by using the F1 key. Three different levels of memory testing can be performed, including Basic, Standard, and Extended. Use a basic test to quickly check the memory. Use the standard test to perform a standard test of the memory. Use the extended test when you want to perform more extensive testing. Set the number of test passes by using the Pass Count option.
To detect system crashes possibly caused by failing memory, memory diagnostics work with the Microsoft Online Crash Analysis tool. If a computer crashes because of failing memory, and memory diagnostics detect this, you are prompted to schedule a memory test the next time the computer is restarted.
Recovering from a failed start
If Windows Server 2012 R2 fails to start, the server typically will go into recovery mode during the next startup. After preparing automated recovery and attempting to diagnose the server, you’ll see an Automatic Repair screen. From this screen, you can select Restart to shut down and start the computer again or Advanced Options to display additional options that might help you repair the server.
If you elect to restart the computer, Windows will do a full restart, which can sometimes resolve the problem. If you choose Advanced Options, you’ll have the following options:
■ Continue Exits the repair menu, and continues to load the operating system.
■ Use Another Operating System Exits the repair menu, and enables you to select the operating system to load (if multiple operating system are installed).
■ Troubleshoot Displays the Advanced Options menu.
■ Turn Off Your PC Exits the repair menu, and shuts down the server.
If you select, Troubleshoot, the Advanced Options screen has the following options:
■ System Image Recovery Enables you to recover the server by using a system image file. The image file can come from a remote computer.
■ Command Prompt Enables you to access a command prompt and work with the commands and tools available in the recovery environment.
■ Startup Settings Enables you to change the startup behavior and start the server in safe mode. Here, you click Restart to restart the computer in safe mode so that you can disable driver signature enforcement, early-launch anti-malware protection, and automatically restart on system failure. You can also enable low-resolution video mode, debugging mode, boot logging, and safe mode.
Starting a server in safe mode
Many startup problems occur because something on the system has changed; for example, a device might have been incorrectly installed. The system configuration or registry might have been updated improperly, causing a conflict. Often you can resolve startup issues by using safe mode to recover or troubleshoot system problems. When you have finished using safe mode, be sure to restart the server by using a normal startup. You will then be able to use the server as you usually would.
In safe mode, Windows Server 2012 R2 loads only basic files, services, and drivers. The drivers loaded include those for the mouse, monitor, keyboard, mass storage, and base video. The monitor driver sets the basic settings and modes for the server’s monitor; the base video driver sets the basic options for the server’s graphics card. No networking services or drivers are started unless you choose the Safe Mode With Networking option. Because safe mode loads a limited set of configuration information, it can help you troubleshoot problems.
You can start a server in safe mode by following these steps:
1. If the computer won’t start as usual, the Recovery screen is displayed during startup. On the Recovery screen, tap or click Troubleshoot.
2. On the Advanced Options screen, tap or click Startup Settings. Next, on the Windows Startup Settings screen, tap or click Restart.
3. Use the arrow keys to select the safe mode you want to use, and then press Enter. The safe mode option you use depends on the type of problem you’re experiencing. The key options are as follows:
■ Repair Your Computer Loads the Startup Repair tool. Choose this option to restart the server and go back to the Recovery screen.
■ Safe Mode Loads only basic files, services, and drivers during the initialization sequence. The drivers loaded include the mouse, monitor, keyboard, mass storage, and base video. No networking services or drivers are started.
■ Safe Mode With Networking Loads basic files, services, and drivers, in addition to services and drivers needed to start networking.