L14_Storage - EE504 Lecture 15 Storage Systems Dr. Yifong...

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EE504 Lecture 15 Storage Systems Dr. Yifong Shih Northwestern Polytechnic University Spring 2008 Based on Prof. David Patterson’s slides
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2 Case for Storage Shift in focus from computation to communication and storage of information E.g., Cray Research/Thinking Machines vs. Google/Yahoo “The Computing Revolution” (1960s to 1980s) “The Information Age” (1990 to today) Storage emphasizes reliability and scalability as well as cost-performance What is “Software king” that determines which HW features used? Operating System for storage Compiler for processor Also has own performance theory—queuing theory—balances throughput vs. response time
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3 Outline Magnetic Disks RAID Advanced Dependability/Reliability/Availability Conclusion
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4 Disk Figure of Merit: Areal Density Bits recorded along a track Metric is Bits Per Inch ( BPI ) Number of tracks per surface Metric is Tracks Per Inch ( TPI ) Disk Designs Brag about bit density per unit area Metric is Bits Per Square Inch : Areal Density = BPI x TPI Year Areal Density 1973 2 1979 8 1989 63 1997 3,090 2000 17,100 2006 130,000 1 10 100 1,000 10,000 100,000 1,000,000 1970 1980 1990 2000 2010 Year Areal Density
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5 Historical Perspective 1956 IBM Ramac — early 1970s Winchester Developed for mainframe computers, proprietary interfaces Steady shrink in form factor: 27 in. to 14 in. Form factor and capacity drives market more than performance 1970s developments 5.25 inch floppy disk formfactor (microcode into mainframe) Emergence of industry standard disk interfaces Early 1980s: PCs and first generation workstations Mid 1980s: Client/server computing Centralized storage on file server » accelerates disk downsizing: 8 inch to 5.25 Mass market disk drives become a reality » industry standards: SCSI, IPI, IDE » 5.25 inch to 3.5 inch drives for PCs, End of proprietary interfaces 1990s: Laptops => 2.5 inch drives 2000s: What new devices leading to new drives?
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6 Future Disk Size and Performance Continued advance in capacity (60%/yr) and bandwidth (40%/yr) Slow improvement in seek, rotation (8%/yr) Time to read whole disk Year Sequentially Randomly (1 sector/seek) 1990 4 minutes 6 hours 2000 12 minutes 1 week(!) 2006 56 minutes 3 weeks (SCSI) 2006 171 minutes 7 weeks (SATA)
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7 Use Arrays of Small Disks? 14” 10” 5.25” 3.5” 3.5” Disk Array: 1 disk design Conventional: 4 disk designs Low End High End Katz and Patterson asked in 1987: Can smaller disks be used to close gap in performance between disks and CPUs?
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8 Advantages of Small Formfactor Disk Drives Low cost/MB High MB/volume High MB/watt Low cost/Actuator Cost and Environmental Efficiencies
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9 Replace Small Number of Large Disks with Large Number of Small Disks! (1988 Disks) Capacity Volume Power Data Rate I/O Rate MTTF Cost IBM 3390K 20 GBytes 97 cu. ft.
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This note was uploaded on 01/19/2011 for the course EE EE504 taught by Professor Drlao during the Fall '10 term at College of the North Atlantic.

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L14_Storage - EE504 Lecture 15 Storage Systems Dr. Yifong...

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