Comparison Item | UEFI Boot Mode | Legacy BIOS Boot Mode |
System Boot Process | UEFI utilizes GPT (GUID Partition Table) as its partition scheme and supports hard disks larger than 2TB and multiple partitions. | Legacy BIOS employs the MBR (Master Boot Record) as its partition scheme, supporting hard disks up to 2TB and a maximum of four primary partitions. |
Boot Speed | UEFI provides a faster booting speed as it can directly interact with the operating system. | Legacy BIOS has to load the operating system via a boot loader. |
Secure Boot | UEFI offers the Secure Boot feature, which can prevent unauthorized operating systems and boot loaders from booting. | Legacy BIOS does not have a Secure Boot feature like UEFI. |
User Interface and Operations | UEFI provides a graphical interface and a wider range of operation options. | Legacy BIOS typically provides a basic text-mode interface. |
Compatibility | UEFI is a relatively new technology, supporting more hardwares and operating systems. | Legacy BIOS is a relatively old technology that may encounter compatibility issues on certain new hardwares and operating systems. |
Firmware Size | UEFI firmware is typically larger in size than Legacy BIOS firmware due to its incorporation of more features and drivers. | Legacy BIOS firmware is typically smaller in size than UEFI firmware. |
System Diagnostics and Recovery | UEFI boot mode generally offers a more comprehensive set of system diagnostic and recovery tools, aiding in an easier system repair and recovery process when issues arise. | Compared to UEFI, Legacy BIOS has a less extensive set of system diagnostic and recovery tools. |
Boot Mode | Instance Type |
Only supports Legacy BIOS | CVM_x86 models: Old-generation models such as Standard S1/S2/S2ne, Memory Optimized M1/M2, High IO I1/I2, Compute Optimized C2/CN2, and Big Data D1, and so on. Bare Metal: All bare metal models support only Legacy BIOS. HCC: Standard HCCS5, HCCIC5, HCCPNV4h, HCCG5vm, and HCCG5v. |
Only supports UEFI | HCC: GPU model HCCPNV5. ARM Models: Only UEFI boot mode is supported. |
Compatible with both Legacy BIOS and UEFI | CVM_x86 Models: Except some old-generation models that only support the Legacy BIOS boot mode, the other new generation CVM_x86 models are compatible with these two boot modes. Heterogeneous GPU Models: Compatible with these two boot modes. |
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