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Hitachi

Corporate InformationResearch & Development

August 21, 2013

Report from Presenter

The 15th International Conference on Enterprise Information Systems (ICEIS 2013) was held in Angers, France during 4th to 7th July 2013. This conference widely covered many topics such as enterprise information systems, database, systems integration, and decision support system.

Yokohama Research Laboratory (YRL), Hitachi Ltd. presented a paper titled "Data Location Optimization Method to Improve Tiered Storage Performance."


Fig. 1 Problem with existing method
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Fig. 2 Proposed method
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With recent improvements in information technology, the amount of access workload to information systems is increasing. In General, input and output (I/O) activities have a locality, and the number of I/Os for each area is different. Therefore, if frequently accessed areas are stored on SSDs (Solid State Drives) that have high performance and are expensive, and rarely accessed areas are stored on HDDs (Hard Disk Drives) that have low performance and are inexpensive, I/O performance will increase and system cost will be reduced. However, frequent data location optimization would result in frequent data movements between SSDs and HDDs. On the other hand, when the data location is rarely optimized, frequently accessed areas would remain allocated to HDDs. As a result, system I/O performance would decrease.

We proposed a new method to allocate frequently accessed areas to SSDs using two different optimization frequencies. Even if pages that have been frequently accessed for a long time become rarely accessed, it is anticipated that this change is temporary and that the pages will become frequently accessed again. Therefore, areas that are frequently accessed for a short time as well as areas that are frequently accessed for a long time should be allocated to SSDs. We confirmed that the proposed method improves I/O performance compared to the existing method without increasing the data movement between SSDs and HDDs by simulation.

(By HAYASHI Shinichi)

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