The term BIOS / UEFI refers to two generations of firmware that are crucial for the startup and basic configuration of every computer, including servers.
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BIOS stands for Basic Input/Output System.
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UEFI stands for Unified Extensible Firmware Interface.
This is software stored in memory on the motherboard, which is launched immediately after the server (or other computer) is powered on, even before the operating system itself. Its main task is to initialize hardware, perform basic component tests (known as Power-On Self-Test – POST), and then hand over control to the bootloader, which loads the operating system.
Differences and Significance for Server Administrators:
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BIOS (older generation):
- Uses 16-bit mode.
- Has limited disk support (maximum 2TB) and uses the MBR (Master Boot Record) disk partitioning scheme.
- Typically offers a text-based user interface.
- Slower system startup.
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UEFI (modern generation):
- Successor to BIOS, bringing a more modern architecture (32-bit or 64-bit mode).
- Supports larger disks (more than 2TB) thanks to the GPT (GUID Partition Table) disk partitioning scheme.
- Often offers a graphical user interface with mouse support.
- Allows for faster system startup.
- Includes the Secure Boot feature, which enhances security by preventing unauthorized firmware and operating systems from booting.
- Has more advanced network boot functions (e.g., PXE).
Practical Use in the Context of Server Management:
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Boot settings: A server administrator often needs to change the boot order (e.g., boot from USB, CD/DVD, network – PXE) for operating system installation or recovery.
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Hardware configuration: Here, parameters such as virtualization (VT-x/AMD-V), RAID controllers, memory frequencies, or sensor monitoring (temperatures, fan speeds) are set.
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Firmware updates: Regular updates of BIOS/UEFI firmware are crucial for server stability, performance, and security. New versions often fix bugs, add support for new hardware, or patch security vulnerabilities.
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Security: Enabling Secure Boot in UEFI is an important security feature for servers, especially in sensitive environments.
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Remote management: For servers with IPMI (Intelligent Platform Management Interface) or similar technologies (e.g., Dell iDRAC, HP iLO), it is possible to access the BIOS/UEFI interface remotely, which allows for complete server management even before the OS starts.
