Critical Issues and Solutions for Virtual Servers

Critical Issue: Unexpected Reboot of Virtual Server

One of the most common critical issues in virtual servers (VDS) is the unexpected reboot of the server. This problem usually occurs due to kernel errors or misconfigurations. In this article, we will provide a step-by-step guide to resolve server reboot issues.

Identifying the Source of the Issue

First, we need to check the syslog file to understand the reasons for the server's reboot. View the log file with the following command:

sudo less /var/log/syslog

Search the log file for kernel panic or OOM (Out of Memory) errors to identify the source of the issue. If you see a kernel panic error, there may be a problem with the kernel configuration.

Fixing Kernel Panic Errors

If you encounter a kernel panic error, you can follow these steps:

• Step 1: Access the GRUB menu to boot the server in safe mode. Reboot the server and hold down the Shift key during startup.
• Step 2: In the GRUB menu, select Advanced options for Ubuntu and boot into recovery mode.
• Step 3: In recovery mode, select root to access the command line.
• Step 4: Use the following command to check the file system:

fsck -f /dev/sda1

• Step 5: If there are file system errors, correct them and reboot the server in normal mode:

reboot

Managing High Memory Usage

If you receive an OOM error, you will need to optimize memory management on the server. Reducing the swappiness setting can help you use memory more efficiently. Check the current swappiness value with the following command:

cat /proc/sys/vm/swappiness

The default value is usually 60. To reduce it to 10:

echo 10 | sudo tee /proc/sys/vm/swappiness

To make this change permanent, edit the /etc/sysctl.conf file:

sudo nano /etc/sysctl.conf

Add the following line at the end of the file:

vm.swappiness=10

Apply the changes by running the following command:

sudo sysctl -p

Enhancing Server Performance

To improve server performance, it is also important to optimize web servers like Apache or Nginx. You can optimize the Apache server with the following steps:

• Step 1: Enable the mpm_prefork module:

sudo a2enmod mpm_prefork

• Step 2: Edit the apache2.conf file:

sudo nano /etc/apache2/apache2.conf

Edit the following parameters:

StartServers 5
MinSpareServers 5
MaxSpareServers 10
MaxRequestWorkers 150
MaxConnectionsPerChild 3000

• Step 3: Restart the Apache server:

sudo systemctl restart apache2

Conclusion

In this article, we provided a detailed guide on critical issue resolutions that you may encounter in virtual servers. Don't forget to regularly check your system to prevent critical errors and enhance server performance.