💽 MBR vs GPT — Overview
| Feature | MBR (Master Boot Record) | GPT (GUID Partition Table) |
|---|---|---|
| 📅 Introduced | 1983 (IBM PC standard) | 2005+ (part of UEFI spec) |
| 🧠 Full Form | Master Boot Record | GUID Partition Table |
| 🛠️ Max Partitions | 4 (Primary) or 3 + 1 extended | 128 (on Windows) |
| 💾 Max Disk Size | 2 TB | ~9.4 ZB (Zettabytes) |
| 📍 Partition Table Location | At start of disk | Spread across disk (main + backup) |
| 🔄 Boot Mode Support | BIOS (legacy) | UEFI (modern) |
| 💣 Recovery Support | ❌ No backup of partition table | ✅ Stores a backup at end of disk |
| 🛡️ Corruption Protection | ❌ None | ✅ Uses CRC32 checksums for validation |
| 🧾 Unique Partition IDs | ❌ No | ✅ Uses 128-bit GUIDs per partition |
🔧 What Is a Partition Table?
The partition table tells the system:
-
How the disk is divided into regions (partitions)
-
Where each partition starts and ends
-
Which partition is bootable
🔍 Key Differences Explained
1. 🧱 Partition Limits
-
MBR: Only 4 primary partitions allowed.
- Workaround: Use 1 extended partition, then create logical partitions inside it.
-
GPT: Directly supports up to 128 partitions without hacks.
2. 💾 Disk Size Limitations
-
MBR: Uses 32-bit addressing → max size = 2 TB
-
GPT: Uses 64-bit addressing → max size = ~9.4 zettabytes
GPT is required for modern SSDs and large-capacity HDDs.
3. 🛑 Data Integrity
-
GPT: Stores a backup of the partition table at the end of the disk and uses CRC checksums for integrity.
-
MBR: No backup, no checksums → easily corrupted.
4. 🧠 Boot Mode Compatibility
| Scheme | Works with |
|---|---|
| MBR | BIOS only |
| GPT | UEFI only (modern) |
Modern PCs with UEFI firmware usually require GPT for booting.
🧪 Real-World Usage
| Use Case | Recommended Scheme |
|---|---|
| Old systems or OSes (e.g. Windows XP) | MBR |
| Modern Windows (8/10/11), Linux, macOS | GPT |
| Disks > 2 TB | GPT only |
| Dual-booting old & new OS | Maybe MBR for compatibility, but GPT preferred if UEFI supported |
🧠 Interview-Ready Summary:
MBR (Master Boot Record) is the legacy disk partitioning scheme limited to 4 partitions and 2 TB of disk space, compatible with BIOS booting. GPT (GUID Partition Table) is the modern replacement used with UEFI, supporting large disks, up to 128 partitions, and better data integrity via checksums and backup tables.