Evolutionary Storage

Evolutionary Storage

Evolutionary Storage is proposed to counteract the disk devolution process. Degradation in performance over time is a serious and common concern in magnetic disks. Sometimes, people benchmark their disks when new, and then many months later, and are surprised to find that the disk is getting slower. In fact, the disk most likely has not changed at all, but the second benchmark may have been run on tracks closer to the center of the disk. Modern hard disks employ [http://www.pcguide.com/ref/hdd/geom/tracksZBR-c.html zoned bit recording (ZBR)] : tracks are grouped into zones. The raw data transfer rate of the disk when reading the outside cylinders is much higher than when reading the inside ones. This is because the tracks on the outside are much longer than the ones on the inside, typically doubling the circumference or more, therefore containing more data, but the angular velocity of the platters is constant regardless of which track is being read.

An evolutionary storage system uses object frequency to cluster frequent data. It is a conceptually simple technique for dramatically improving disk performance. Two different three-level architectures may be used: inner-outer-cache (fast band disk implementation as a comparison) and disk-flash-cache ( [http://www.samsung.com/Products/HardDiskDrive/news/HardDiskDrive_20050425_0000117556.htm Hybrid Disk] implementation). Using a real system disk trace, the experimental results showed that the performance speedup due to the disk re-organization is 2.4 for the fast band disk and 4.0 for the hybrid disk, respectively. The Hybrid Disk outplays the fast band disk at little additional cost on a flash memory.

This technique can be implemented in a device driver (or controller). No changes to the file system are required. This is a “black box” design, which automatically infers object frequency in a disk drive. Unlike this, “White Box” or “Gray Box” design relies on storage front-ends, such as a file system, to directly or indirectly pass semantic information to obtain object frequency in a storage system.

The strategy is to move data to their optimal locations during idle periods, so as not to conflict with system use. Much of the benefit of disk re-organizing could be obtained from reorganizing only 10% of the data. For example, it takes less than 1 hour to move 50% of fast band data out of the fast band and 1 hour to move the same amount of data to fill the fast band. It is still practical for a storage system, because frequency distribution is relatively stable, it is unnecessary to keep swapping the data between the fast band/flash memory and slow band. Instead, it might be acceptable to spend one hour every week on running Object Mover to update the layout.

References

#Frank Wang, Yuhui Deng, Na Helian, Evolutionary Storage: Speeding up a Magnetic Disk by Clustering Frequent Data, IEEE Transactions on Magnetics, ISSN 00189464, Issue.6, Vol.43, 2007.


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Evolutionary informatics — is a subfield of informatics addressing the practice of information processing in, and the engineering of information systems for, the study of biological evolution, as well as the study of information in evolutionary systems, natural and… …   Wikipedia

  • Evolutionary Informatics Lab — The Evolutionary Informatics Lab is a cyberspace entity created in 2007 by Baylor University professor Robert J. Marks II conducting research on mathematical details purported to underly intelligent design [ Most of these critics are responding… …   Wikipedia

  • Grid-oriented storage — (GOS) is a dedicated data storage architecture which can be connected directly to a computational grid to support advanced data bank services and reservoirs for data that can be shared among multiple computers and end users on the grid.… …   Wikipedia

  • Plant evolutionary developmental biology — For a more ecological discussion on the evolution of plant morphology, refer to Evolutionary history of plants Evolutionary developmental biology (evo devo) refers to the study of developmental programs and patterns from an evolutionary… …   Wikipedia

  • angiosperm — /an jee euh sperrm /, n. Bot. a plant having its seeds enclosed in an ovary; a flowering plant. Cf. gymnosperm. [ANGIO + SPERM] * * * ▪ plant Introduction       any member of the more than 300,000 species of flowering plants (division Anthophyta) …   Universalium

  • Life Sciences — ▪ 2009 Introduction Zoology       In 2008 several zoological studies provided new insights into how species life history traits (such as the timing of reproduction or the length of life of adult individuals) are derived in part as responses to… …   Universalium

  • algae — algal, adj. /al jee/, n.pl., sing. alga / geuh/. any of numerous groups of chlorophyll containing, mainly aquatic eukaryotic organisms ranging from microscopic single celled forms to multicellular forms 100 ft. (30 m) or more long, distinguished… …   Universalium

  • Anthropology and Archaeology — ▪ 2009 Introduction Anthropology       Among the key developments in 2008 in the field of physical anthropology was the discovery by a large interdisciplinary team of Spanish and American scientists in northern Spain of a partial mandible (lower… …   Universalium

  • plant — plantable, adj. plantless, adj. plantlike, adj. /plant, plahnt/, n. 1. any member of the kingdom Plantae, comprising multicellular organisms that typically produce their own food from inorganic matter by the process of photosynthesis and that… …   Universalium

  • Artificial intelligence — AI redirects here. For other uses, see Ai. For other uses, see Artificial intelligence (disambiguation). TOPIO, a humanoid robot, played table tennis at Tokyo International Robot Exhibition (IREX) 2009.[1] Artificial intelligence ( …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”