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					     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 x.ping@huawei.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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Description: 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.