Raid Level Comparison
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:
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.