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Conclusion: Capacity And Performance Scale Together

SSDs In RAID: A Performance Scaling Analysis
By , Achim Roos

This test of SSDs in a RAID 0 array brings to light an interesting effect: adding more drives increases performance and capacity in equal measure. The same conclusion applies both to data throughput and I/O operations per second.

Performance scales almost linearly in our test system, each added drive offering roughly the same increase. When it comes to I/O performance, we did not run into any upper limits or decreasing scaleability when adding drives, so you should be able to extrapolate the results for your own scenario up to the bandwidth and latency limits of your platform architecture. Expanding capacity brings equal performance increases with SSD RAID, which is a first in this area.

Of course, the results cannot be perfectly applied to all RAID systems, but the test brings a key finding: an SSD-based RAID array benefits much more from adding more drives compared to traditional hard drives. The more flash drives involved, the greater their strengths become, especially the I/O performance that is so crucial in the business segment. While you probably won't see RAID 0 arrays like these used in many production servers (they'd be a little more plausible in a video workstation, perhaps), there are other performance-enhancing RAID modes you could use to augment the speed and reliability of a mission-critical system.

For enterprises, this provides a new criterion that should be considered when planning an SSD RAID system. In addition to the prices of flash drives, controllers, and the server platfrom, one also has to take into account the number of drives that are going to be used. However, the test results show that the strengths of SSD RAID can only be properly exploited in an appropriate environment, such as a high-speed data access-dependent Web or file server.

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