Conclusion
The Intel X25-E SATA Solid-State Drive provides a cost-effective option for hybrid arrays with an SSD-based tier-0. As an example, Atrato has been able to integrate the Intel X25-E SATA Solid-State Drives in the V1000 tier-0 and with the overall virtualization software for the SAID so that performance can be doubled or even quadrupled.
The use of RAM cache for storage I/O is hugely expensive and very difficult to scale given the cost as well as the complexity of scalable memory controllers like FB-DIMM or R-DIMM beyond terabyte scale. Solid state drives are a better match for HDDs, while being an order of magnitude faster for random IOPs and providing the right amount of additional performance for the additional cost, providing for easily justifiable expense to obtain comparable application speed-up.
The use of SSDs as drive replacements in embedded applications is inevitable and simple. On the small scale of embedded digital cameras and similar mobile storage devices, SSDs will meet a growing need for high performance, durable, low power direct-attach storage. For larger scale RAID systems, SSDs in hybrid configurations meet ingest, egress, and access cache needs far better than RAM and at much lower cost. Until SSD cost per gigabyte reaches better parity with HDD, which may never happen, hybrid HDD+SSD is here to stay, and many RAID vendors will adopt tiered SSD solutions given the cost/benefit advantage.
Acknowledgements
Nick Nielsen (Senior Software Engineer), Phillip Clark (Senior Software Engineer), Lars Boehenke (Software Engineer), Louis Morrison (Senior Electrical Design Engineer), and the entire Atrato, Inc. team who have all contributed to the ApplicationSmart software and integration of solid state disks with the V1000 intelligent RAID system.
References
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This article and more on similar subjects may be found in the Intel Technology Journal, March 2009 Edition, "Advances in Embedded Systems Technology". More information can be found at http://intel.com/technology/itj.
