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DDR, also known as double data rate SDRAM Dual Date Rate SDRSM DDR SDRAM is a high-speed CMOS dynamic random access memory JEDEC Solid State Technology Association, the United States in June 2000 announced a double data rate synchronous DRAM (DDR SDRAM) standard JESD79 because it trigger edge of the clock can be up and down along the data transmission so even in the 133MHz bus frequency bandwidth can achieve 2.128GB / s DDR voltage of 3.3V is not supported but support a 2.5V LVTTL SSTL2 it can still follow the now standard production system with SDRAM SDRAM manufacturing cost is slightly higher than some, but far less than the price of Rambus DDR memory represents the future to compete with Rambu memory development in one direction.
Storage & Security Solid state disk starts a low-carbon revolution SSD Solid state disk starts a low-carbon revolution Moore’s Law for the computer system By Du Yumin T he major three components of a computer system, the CPU, memory, and hard disk have been developing at different paces. Since 1997, hard disk and memory capacities have been increasing at a rate outpacing Moore’s Law, while the performances of the CPU, I/O device, and memory have basically been in line with it. Today’s mainstream X86 CPU, whose dominant frequency has already exceeded 3GHz, delivers more than one billion read/write instructions per second, or 1,000 million instructions per second (MIPS) when working with technologies such as multi-kernel, multi-streamline, and multi-thread. Memory technology is so developed that DDR3 will soon be replaced by DDR4 that will support more than 100,000 read/write operations every second. U n f o r t u n a t e l y, h a r d d i s k performance has been developing at a relatively slow pace, having increased only 1.5 times in the past decade. Today, a SATA hard disk allows a maximum of 150 read/write operations per second (80 operations/second on average), and even a high-performance FC or SAS hard disk only allows 300 input/output operations per second (IOPS). 39 MAR 2011 . ISSUE 59 Huawei Communicate Why is there such an imbalance between the perform10000IOPS while consuming only development of CPUs and hard disks? 2.5W of power. The HSSD, developed recently A conventional mechanical hard disk is by Huawei Symantec, allows for 35,000 IOPS manufactured using magnetic disk sheets and (read) and 10,000 (write) per second, improving its performance is in direct proportion to the the processing speed by 100 times over an FC rotational speed of the magnetic disk sheets. Since hard disk. This completely removes the hard disk 1997, the rotational speed of SATA disk sheets has performance bottleneck of the computer system. increased by 33% from 5,400 to 7,200rpm while An SSD not only offers users higher speed when that of FC and SAS disk sheets has increased by using a computer but also provides the following 50% from 10,000 to 15,000rpm. However, if the features. rotational speed of disk sheets increases further, Zero noise. When a hard disk is reading or the hard disk will consume more power since the writing data, there is friction between the read/ power consumption of a mechanical hard disk is write head and rotating disk sheets, generating 10 directly proportional to 2.8th power of the disk to 20dB of noise. But an SSD does not generate sheets’ rotational speed. The power consumption any noise because it uses electronic flash memory of the existing hard disk has reached the limit of chips instead of mechanical devices such as motors. the computer system, leaving no room for further Extended lifecycle. While a reliable FC hard performance improvement. disk can run for 1.2 million hours, an SSD We are left with a frustrating situation: The can run for 2.4 million hours, because it is free overall performance of a computer system will from mechanical wear and tear and has built-in deteriorate sharply, only allowing for a maximum reliability algorithms such as the flash bad block of 300 read/write operations per second when management algorithm and data verification writing or reading data on hard disks, regardless of algorithm in its CPU. the speeds of the CPU and memory unit. How can Energy and cost efficiency. When starting, we find a way of breaking this bottleneck so that the rotation of a mechanical hard disk accelerates hard disk performance can develop in line with from 0 to 15,000rpm and the starting current Moore’s Law? – This is a challenge facing ICT. is three times higher than its average working current. In addition, the extra current generated SSD fully improves hard disk during a read/write operation is 2.5 times higher than its average working current. In other words, performance a computer system must be able to ensure 50W or higher to support a 20W hard disk, which requires Unlike a mechanical hard disk, an SSD uses an the design of higher power redundancy for the electronic flash chip as its data storage medium. system power supply unit and therefore increases An SSD is actually a mini computer system and the system costs. The starting current of an SSD is has its own CPU, memory unit, and storage unit. only 5% higher than its average working current However, it uses ARM or PowerPC that consumes because it is composed entirely of electronic less power than the X86 CPU and adopts flash components. While working, the SSD keeps its memory chips instead of a hard disk as its storage working current stable without generating any unit at the backend. A compact storage unit that extra current, ensuring high system reliability. ensures security and rapid operations, a flash Superb random read/write capability. When memory chip provides large capacity and features a conventional hard disk reads or writes data, the low power consumption. It ensures zero data loss read/write head must keep moving or waiting until in case of a power failure. One flash memory the target data sector turns under the read/write chip allows 2,000 to 4,000 read/write operations head if data is randomly distributed on the disk. per second with its power consumption below This dramatically reduces read/write efficiency. 150mW. Currently, an SSD supports a maximum Even for an FC hard disk, the random read/write of 128 flash memory chips. efficiency is below 100IOPS. In comparison, an With its own complete computing system, the SSD only needs to check up a table, locate the SSD can be imbedded with flash-supported fine- flash memory chip where data is stored, and then tuning algorithms. Further, it allows multiple read/write data accordingly. Therefore, an SSD’s flash memory chips to perform concurrent read/ random read/write performance is very close to its write operations. Therefore, an SSD can easily sequential read/write performance. For web servers, MAR 2011 . ISSUE 59 40 Storage & Security Solid state disk starts a low-carbon revolution database servers, and file servers that require high material, processing, transportation, use, and random read/write performance, SSDs are the best recycling within five years. In contrast, an SSD choice as they can boost the performance by 100 discharges a mere 110kg of carbon dioxide in the times at least. same period. In other words, using an SSD other Superb adaptability. A conventional hard than a conventional hard disk is equivalent to disk rotates by 15,000rpm. Even a high-precision planting four trees. conventional hard disk is environment-sensitive Furthermore, as the SSD is composed of only and shows poor shockproof performance. With a electronic parts, the price of an SSD will drop power consumption of 17W, a conventional hard by half every 18 or 24 months, at a pace close to disk cannot work in an enclosed high-temperature that defined by Moore’s Law. It is predicted that environment. An SSD, using no mechanical an SSD will cost almost the same as an FC or parts, features strong shockproof capabilities SAS hard disk in three years time and SSDs will and is adaptive to all environments: natural heat supersede FC or SAS hard disks in mainstream dissipation, enclosed space, ultra-low temperatures. storage markets. The SSD developed by Huawei Symantec was used by China’s Antarctica Exploration Team in the South Pole, where it worked well at a temperature Revolution of computer of minus 40 degrees Celsius. system architecture Low-carbon economy leads While helping cut power consumption by computer backend devices and improve the overall the trend performance by more than 100 times, the SSD has a profound influence on computer system Though first developed in 1989, the SSD is not architecture and will further push the development yet widely used today. High price has been one of the CPU and memory. In addition, it improves of the major constraints, for the price of a high- the percentage of computer parts influenced by performance SSD is seven times higher than that of Moore’s Law so that the computer system can an FC hard disk. Actually, the SSD helps customers develop at the pace defined by the Law. Thanks reduce expenditure considerably, especially in to the SSD, the computer system is transforming applications requiring high read/write efficiency. into a low-carbon IT system with ever-improving We can compare the operational expenditure energy/efficiency ratio. incurred by using the SSD and the FC hard In the future, a high-end computer system, which disk over a span of five years. When running at is based on servers and storage arrays, will consist of 10,000IOPS, an SSD is 30 times faster than an FC four major parts: the CPU, memory unit, SSD, and hard disk in data processing but consumes only 1/7 mechanical hard disk. Real-time access data will be of the power otherwise consumed by the FC hard stored in the memory unit; non-volatile data that disk. On an IOPS per watt (IOPS/W) basis, one requires high read/write performance will be stored SSD is equivalent to 210 FC or SAS hard disks. on the SSD, and files that do not require high read/ This means that a computer system using a write performance will be stored in hard disks. This conventional hard disk has to consume a power will ensure not only high system performance but of 510W to ensure 10,000IOPS, but a computer also a large storage capacity, thereby reducing system system using an SSD requires only 2.5W. costs and balancing the system performance/price According to Energy Star, 1W power saved in ratio and energy/efficiency ratio. a hard disk means a 1.85W power reduction in The computer has changed the course of human a user’s computer system or telecom equipment history and is now part of people’s everyday lives. room. When calculated by RMB1 for 1KW, a With computer technologies advancing, the SSD computer system that requires a performance of will probably change the world again by changing 10,000IOPS can save RMB60,000 (USD9,100) the computer system. within five years by using only one SSD – a benefit Editor: Xu Ping email@example.com well above the cost of an SSD. A lifecycle analysis (LCA) of the FC hard disk Thanks for your reading, the electronic version and subscription and SSD shows that an FC hard disk emits 525kg information are available at www.huawei.com/communicate. Questions and suggestions may be directed to the editor concerned. of carbon dioxide during its lifecycle from raw 41 MAR 2011 . ISSUE 59
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