Design and Software Support of Hybrid Storag Devices
Date Issued
2009
Date
2009
Author(s)
Chang, Hao-Hsiang
Abstract
In the recent years, the gap between the CPU performance and the hard disk drive performance becomes larger as the technology has not been able to reduce the disk seek time signi cantly. Many research works try to bring this gap closer, e.g. built-in disk cache, data prefetch, ramdisk and solid-state disks, and optimizations in the OS for block IO devices. However, other issues such as the manufacturing cost, the consistency and safety of data, and power consumption are also important concerns. In this thesis, we propose a storage virtualization mechanism to handle hybrid random-access storage devices made with solid-state disks, ramdisks, and hard disks. By implementing a con gurable, software cache driver based on the Linux device-mapper, the users can automatically take the advantage of the faster disk without the need to move frequently-used data from a slower storage device onto aaster storage device.e used several benchmarks to evaluate the proposed scheme. In the postmark benchmark, the average disk access time of our hybrid storage device was improved by 292% compared to the hard disk only. For finding the optimal con figuration for a particular application, we developed a trace-driven simulator to explore the search space. The simulator works with blktrace, an IO trace collection tool available oninux platform, to simulate the disk access pattern of an application with a variety of cache con figurations. With the simulation tool, the performance with a hybrid storageevice can be evaluated effectively before the actual purchase. Meanwhile, the time needed for installing the storage system and experimenting with the workload canlso be saved.
Subjects
Storage Virtualization
Hybrid Storage
Disk Cache
Device-Mapper
ramdisk
SSD
Type
thesis
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