Raid Level Comparison
Drives used for test:
Toshiba X300 Extreme Performance HDD, 6TB (HDW160EZSTA)
(link)
Technical specs:
3,5“ mechanical HDD • 7.200rpm • Cache: 128MB • power consumption: 11.3W, 6W (idle) • Perpendicular Magnetic Recording (PMR) • sectors: 4KB (Emulation 512e), integrated shock sensor, weight: 720g, interface: SATA 6 Gbit/s
in Part 5 we talked about The Myth of Redundancy in Data Storage and learned something about reliability and redundancy. But what will be happen, when using a modern, state-of-the-art mass storages, such a high performance Toshiba hard drive.
Measured Single drive performance:
|
Performance Test (MB/sec) | Read aver. | Read max. | Write aver. | Write max. |
| HD Tune Pro sequential: | 170.4 | 224.4 | 166.9 | 217.5 | |
| A.S. SSD Benchmark: | 204.8 | 199.7 | |||
| ATTO Disk Benchmark: | 214.5 | 211.3 | |||
| Crystal Disk Mark: | 216 | 214 | |||
| access time: | 10-14 ms | ||||
 8x 6TB Toshiba X300 High Performance Drives |
Calculated RAID Level performances:
(Read/write ratio 50/50%, using 8 Toshiba X300 drives)
| RAID 0 | RAID 5 | RAID 6 | RAID 10 | |
| Single RAID group performance (MB/s): | 1.680 | 672 | 480 | 1120 |
| Total usable storage capacity (TB): | 48 | 42 | 36 | 24 |
| Cost per TB usable: | 33,33 | 38,10 | 44,44 | 66,67 |
| Total costs (USD): | 1.600 | |||
RAID Reliability Calculation:
(using 8x Toshiba X300 drives):
| RAID 5 | RAID 6 | RAID 10 | |
| Drive Annual Failure Rate (%) | 6,05 | ||
| Combined system MTTDLTOTAL: | 2,1 | 693 | 5,2 |
| Probability of data loss over time: | |||
| 1 year | 0,37 | 0,001 | 0,17 |
| 1.5 years | 0,69 | 0,003 | 0,37 |
| 3 years | 0,91 | 0,007 | 0,60 |
| calculated by using RAID type, conservative real world MTBF, LSE rate 1014, replacing failed drive within 48 h, rebuild rate 80% for Toshiba X300 6TB | |||
Conclusion:
As we learned, RAID 0 provide us, comparing to other levels, with real light speed processing.
continue with Part 6, where we figure out, why RAID is not a backup.