NDLI: Hard Disk Drives

Content Provider	ACM Digital Library
Author	Elerath, Jon
Abstract	HDDs (hard-disk drives) are like the bread in a peanut butter and jelly sandwich—sort of an unexciting piece of hardware necessary to hold the “software.” They are simply a means to an end. HDD reliability, however, has always been a significant weak link, perhaps the weak link, in data storage. In the late 1980s people recognized that HDD reliability was inadequate for large data storage systems so redundancy was added at the system level with some brilliant software algorithms, and RAID (redundant array of inexpensive disks) became a reality. RAID moved the reliability requirements from the HDD itself to the system of data disks. Commercial implementations of RAID range from n+1 configurations (mirroring) to the more common RAID-4 and RAID-5, and recently to RAID-6, the n+2 configuration that increases storage system reliability using two redundant disks (dual parity). Additionally, reliability at the RAID group level has been favorably enhanced because HDD reliability has been improving as well.
Starting Page	28
Ending Page	37
Page Count	10
File Format	PDF
ISSN	15427730 15427749
DOI	10.1145/1317394.1317403
Journal	Queue (QUEUE)
Volume Number	5
Issue Number	6
Language	English
Publisher	Association for Computing Machinery (ACM)
Publisher Date	2010-04-01
Publisher Place	New York
Access Restriction	One Nation One Subscription (ONOS)
Content Type	Text
Resource Type	Article
Subject	Computer Science Computer Science

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Hard Disk Drives