Chapter 5

1. Chapter 5 Hardware and Software Trends

2. Introduction • Four key areas have fueled the advances in telecommunications and computing • Semiconductor fabrication • Magnetic recording • Networking and communications systems • Software development

3. Exponential Growth • Gordon Moore (a founder of Intel) observed a trend in semiconductor growth in 1965 that has held firm for close to 40 years • Moore’s Law states that the number of transistors on an integrated circuit doubles every 18 months • Similar performance curves exist in the telecommunication and magnetic recording industries

4. Semiconductor Technology • The transistor was invented at Bell Labs in 1947 by John Bardeen, Walter Brattain, and William Shockley • Semiconductors form the foundation upon which much of the modern information industry is based • Advances in process have allowed system designers to pack more performance into more devices at decreased cost

5. Trends in Semiconductor Technology • Diminishing device size • Increasing density of devices on chips • Faster switching speeds • Expanded function per chip • Increased reliability • Rapidly declining unit cost

6. Semiconductor Performance • Electricity (electrons) moves at speeds close to the speed of light (186k miles/sec) • As switching elements of a semiconductor get smaller, they can be placed physically closer together • Since the absolute distance between elements shrinks, device speed increases • Semiconductor manufacturing cost is more related to number of chips produced rather than number of devices per chip

7. Semiconductor Performance • As device size shrinks, performance improves and capability increases (more logic elements in the same size package and those elements operate faster) • During the period from 1960 to 1990 density grew by 7 orders of magnitude • 3 circuits to 3 million • By 2020, chips will hold between 1 to 10 billion circuits

9. Semiconductor Processes • Semiconductors are produced in processing plants called fabs • Fabs produce semiconductors on silicon wafers • The wafers are sliced from extremely pure silicon ingots and polished • These wafers can range in size from 6 to 12 inches (150 to 300 mm) in diameter • Newer fabs process larger wafers

10. Semiconductor Processes • Current state of the art fabs process 300 mm wafers • It costs $1.7 billion dollars and takes 30 months to construct and equip a fab • Fabs are completely obsolete, on average, in seven years

11. Semiconductor Processes • Each wafer holds many identical copies of the semiconductor • The wafer moves from process to process across the fab, slowly being built up to create the final product • The last step in the process slices the wafer up into the individual chips which are tested and packaged

12. Semiconductor Processes • From early in the design of a fab, the number of wafers the plant can process per month is determined • To maximize return on capital investment, the process engineers attempt to produce the greatest number of the highest value chips • Decreasing device size increases both the number of chips per wafer and the speed of the devices produced

13. Semiconductor Processes • The drive to use larger wafers stems from the economies of scale • 2.5 times as many chips can be cut from a 300 mm wafer as compared to a 200 mm wafer • 300 mm fabs cost 1.7 times as much as 200 mm ones

14. Device Geometries • Device geometry is defined by minimum feature size • This is the smallest individual feature created on the device (line, transistor gate, etc.) • Current feature size in leading edge fabs is 0.10 microns • Human hairs are 80 microns in diameter

15. Roadblocks to Device Shrinkage • Most common chips are made using the Complementary Metal Oxide Semiconductor (CMOS) process • Chips using CMOS only consume power when logic states change from 1 to 0 or 0 to 1 • As clock speeds increase the number of logical operations increases

16. Roadblocks to Device Shrinkage • As the minimum feature size decreases, components are closer together and the number of components per unit area increases • Both these factors increase the amount of waste heat needed to be removed from a device • Effectively removing this heat is a big challenge

17. Industry Success • Success of the semiconductor industry is driven by huge budgets for scientific research, process design, and innovation • Since the semiconductor was invented, the industry has experienced a growth rate of 100 times per decade

18. Industry Innovation • Increases in device processing power comes not only from increased clock rates and decreased device sizes • Innovation in physical computer architecture also drives performance • Bus widths have increased from 8 to 16 to 32 and now are growing to 64-bit wide • With wider busses, more data can be transferred from place to place on the chip simultaneously, increasing performance

19. Industry Innovation • Cache Memory – Fast, high speed memory used to buffer program data near the processor to avoid data access delays • Super scalar designs – designs that allow more than one instruction to be executed at a time • Hyperthreading – adding a small amount of extra on-chip hardware that allows one processor to efficiently act as two, boosting performance by 25 %

21. Semiconductor Content • Microprocessors comprise less than 50% of total chip production • Memory, application-specific integrated circuits (ASICs), and custom silicon make up the bulk of production • The telecommunications industry is a huge driver worldwide as cell phone penetration increases

22. Summary • The invention and innovation of the semiconductor industry has been enormously important • Chip densities will continue to increase due to innovation in physics, metallurgy, chemistry, and manufacturing tools and processes • Semiconductors will continue to be cheaper, faster, and more capable

23. Recording Technologies • As dramatic as the progress in semiconductor development is, progress in recording technologies is even more rapid • Disk-based magnetic storage grew at a compounded rate of 25% through the 1980s but then accelerated to 60% in the early 1990s and further increased to in excess of 100% by the turn of the century

24. Exploding Demand • As personal computers have grown in computing power, storage demands have also accelerated • Operating systems and common application suites consume several gigabytes of storage to start with • The World Wide Web requires vast amounts of online storage of information • Disk storage is being integrated into consumer electronics

25. Recording Economics • At current rates of growth, disk capacities are doubling every six months • Growth rates are exceeding Moore’s Law kinetics by a factor of three • Price per megabyte has declined from 4 cents in 1998 to 0.07 cent in 2002

27. Bit Density • Data density for disk drives is measured in bits per square inch called areal density • Current areal density is 70 gigabits per square inch and is expected to climb to 100 gigabits per square inch by the end of 2003 • By 2007, areal densities are expected to exceed 1000 gigabits per square inch

28. Hard Drive Anatomy • Data is stored on hard drives in concentric circles called “Tracks” • Each track is divided into segments called “Sectors” • A drive may contain multiple disks called “Platters” • Writing or reading data is done by small recording heads supported by a mobile arm

29. Hard Drive Performance • Drive performance is commonly measured by how quickly data can be retrieved and written • Two common measures are used • Seek Time • Rotational Delay

30. Hard Drive Performance • Seek Time is the amount of time it takes the heads to move from one track to another • This time is commonly measured in milliseconds (ms or thousandths of a second) • For a processor operating at 1 Ghz, 1 ms is enough time to execute one million instructions • Common seek times of inexpensive drives are from 7 to 9 ms

31. Rotational Delay • The delay imposed by waiting for the correct sector of data to move under the read / write heads • Current drives spin at 7200 RPM. • Faster rotational speeds decrease rotational delay • High end server drives spin at 15000 RPM, with surface speeds exceeding 100 MPH • Heads float on a cushion of air 3 millionths of an inch thick

32. Other Performance Issues • Data transfer interfaces are constantly evolving to keep pace with higher drive performance. • New standards include: • Firewire • USB 2 • InfiniBand

33. Fault-Tolerant Storage • Data has become a strategic asset of most businesses • Loss of data can cripple and sometimes kill an enterprise • Fault-tolerant storage systems have become more important as data availability has become more critical

34. RAID Storage • RAID is an acronym that stands for Redundant Array of Inexpensive Drives • RAIDs spread data across multiple drives to reduce the chance that the failure of one drive would result in data loss • RAID levels commonly range from 0 to 5 with some derivative cases

35. RAID Tradeoffs • Creating data redundancy creates transactional overhead and waste of storage capacity • RAID 1 is also known as disk mirroring where every bit on one disk is duplicated on the mirror • Every transaction takes two reads or two writes, and disk space is half of capacity

36. RAID Tradeoffs • RAID 5 spreads data across multiple disks and creates special error-correcting data • With any drive failure, the lost data can be reconstructed from the remaining data and the error-correcting codes • This has less redundancy than a RAID 1 system, but delivers better throughput

37. RAID Results • Mean time before data loss (MTBDL) is a calculation that attempts to quantify the reliability of a drive • A four-disk storage system without RAID has a MTBDL of 38,600 hours or about once every four years • A five-disk RAID 5 system of equal capacity yields a MTBDL of 48.875 million hours

38. CD-ROM Storage • Five inches in diameter, capable of holding 650 MB of data • So inexpensive, powerful, and widespread are these disks, that many PC manufacturers are discontinuing the sale of 1.44 MB floppy drives in new PCs • CD-R blanks are now costing approximately 5 cents each

39. DVD Storage • DVDs or Digital Versatile Discs • Store 4.7 GB of digital data • Can be used to store video, audio, or larger data archives

40. Autonomous Storage Systems • Computers have traditionally been built with display, compute, and storage subsystems in close physical proximity • With widespread, high speed digital networks, these components no longer need to be in the same physical box • Network Attached Storage and Storage Area Networks are storage examples of this trend

41. Network Attached Storage • A logical extension of the client/server model • NAS boxes are servers not of applications but of storage • Data storage can be centralized so that the disciplines of archiving, security, availability, and restoration are handled by computing professionals, not desktop users

42. Storage Area Networks • Commonly referred to as the “network behind the server” • Create a unified storage architecture that supports the storage needs of multiple servers • Server to storage links are high-speed optical connections using network-like protocols complete with routers and switches

43. Benefits of Storage Systems • Data throughput from a server standpoint and from a storage standpoint must be balanced • Fast servers with slow storage or slow servers with fast storage do not deliver optimal performance • Decoupling storage from computation allows managers to scale each independently

44. Computer Architecture • Computers include: • Memory • Mass storage • Logic • Peripherals • Input devices • Displays

45. Supercomputers • At the extreme edge of the computing spectrum, supercomputers are clusters of individual machines lashed together with high-speed network connections • The 50 most powerful supercomputers in existence today are built of no less than 64 processors • The most powerful are composed of close to 10,000 individual processors

46. Supercomputer Performance • Current benchmarking for supercomputers is the flop or floating-point operations per second • The most powerful supercomputers in the world easily exceed 1 tera-flops • The most powerful machine can attain 35 Tflops

47. Supercomputer Challenges • Effectively harnessing thousands of CPUs together is a very complex programming challenge • Massively parallel computing operating systems are difficult to design, optimize, and troubleshoot

48. Microcomputers • The first microcomputer was sold by IBM in the early 1970s • With the progress of Moore's Law, PCs have become more and more powerful with desktop systems able to deliver in excess of 2500 MIPS (millions of instructions per second) • 10000 MIPS systems will be commonplace by the end of the decade

49. Trends in Systems Architecture • Slowly systems are shifting from being PC focused to network focused

50. Client/Server Computing • With powerful graphical workstations and high-speed networking, PCs have become the user interface engine, not the application • The most obvious example is the Web browser. Any number of servers using numerous different server programs are all accessible by the same Web client