3.2.1. Partition Table Types: GPT vs. MBR
💡 First Principle: A partition table tells the OS where partitions begin and end on a disk. The two standards—MBR and GPT—differ in how much disk space they can address and how many partitions they support. For modern server deployments, GPT is almost always correct.
| Feature | MBR (Master Boot Record) | GPT (GUID Partition Table) |
|---|---|---|
| Max disk size | 2TB | 9.4 ZB (effectively unlimited) |
| Max partitions | 4 primary (or 3 + extended) | 128 per disk |
| Boot support | Legacy BIOS | UEFI (required for UEFI boot) |
| Redundancy | Single partition table | Backup partition table at end of disk |
| Recovery | Harder (single point of failure) | Easier (can recover from backup GPT) |
| Use case | Legacy systems, <2TB boot drives | All modern servers, large drives |
Practical rule: Use GPT for all new server deployments. MBR exists as a legacy concern for older hardware or older OS compatibility.
⚠️ Exam Trap: UEFI boot requires GPT. If you configure a new server with UEFI firmware but partition the boot drive as MBR, the server will not boot from that drive. Legacy BIOS boot requires MBR (or supports both, depending on configuration).
Reflection Question: A new server with UEFI firmware won't boot after OS installation, even though installation appeared to succeed. The drive was partitioned as MBR during setup. What is the problem and how do you fix it?
