Storage & RAID Cheatsheet
Storage & RAID Cheatsheet
RAID levels, storage types, and capacity formulas at a glance.
Storage Types
| HDD (SATA) | 100߀“200 MB/s; ~10 ms latency; cheapest per GB; bulk/backup storage |
| SATA SSD | ~550 MB/s; ~0.1 ms latency; good for OS and general use |
| NVMe SSD (M.2) | 3,000߀“7,000 MB/s; best for OS, databases, high-I/O apps |
| SAS HDD / SSD | Enterprise; dual-port; 10k߀“15k RPM HDDs; higher duty cycle than SATA |
| U.2 / U.3 NVMe | Enterprise NVMe in 2.5" hot-swap form factor; same speed as M.2 |
RAID Levels
| RAID 0 ߀” Stripe | No redundancy; max performance; 1 failure = total data loss; N drives usable |
| RAID 1 ߀” Mirror | 1 drive failure tolerance; 50% usable capacity; fast reads |
| RAID 5 ߀” Parity | 1 failure tolerance; (N-1) usable; min 3 drives; good read performance |
| RAID 6 ߀” Double Parity | 2 failure tolerance; (N-2) usable; min 4 drives; recommended for large arrays |
| RAID 10 (1+0) | 1 failure per mirror pair; 50% usable; min 4 drives; best for databases |
Capacity Formulas
| RAID 0: N G— drive size | e.g. 4 G— 4 TB = 16 TB |
| RAID 1: 1 G— drive size | e.g. 2 G— 4 TB = 4 TB |
| RAID 5: (N-1) G— drive size | e.g. 4 G— 4 TB = 12 TB |
| RAID 6: (N-2) G— drive size | e.g. 6 G— 4 TB = 16 TB |
| RAID 10: N/2 G— drive size | e.g. 4 G— 4 TB = 8 TB |