94674

STORAGE DEVICES

Конспект урока

Иностранные языки, филология и лингвистика

There are ‘internal’ and ‘external’ drives which are both fixed hard drives i. The development of optical technology has resulted in mass storage media such as CD-ROM drives and erasable optical disks. Another reason why CD-ROM is not widely used for ‘personal’ data storage is that CD-ROM drives are slow.

Английский

2015-09-15

122 KB

1 чел.

65

UNIT V

STORAGE DEVICES

INTRODUCTORY TEXT

                                                          Information stored in the RAM is lost

                                        when the computer is turned off. Because of this

                                       data and applications are stored in either hard or floppy disks that provide a more permanent backing store.

Floppy disks are called so because they consists of flexible plastic material which has a magnetizable surface. Sizes vary, but 3.5-inch diameter disks are the most popular.

The surface of a  floppy disk is divided into concentric circles or ‘tracks’, which are then divided into ‘sectors’. When you insert a blank disk into a disk drive, it must be ‘initialized’, or formatted, before information can be recorded onto it. This means that magnetic areas are created for each track and sector, along with a catalogue or ‘directory’ which will record  the specific location of files.

Hard disks have important advantages over floppy disks: they spin at a higher speed, so you can store, retrieve information much faster than with floppies. They can also hold vast amounts of information, from 20 MB up to several hundred gigabytes. Apart from this, both types of disks work in the same way.

When buying a hard disk you should consider the kind of drive mechanisms and products available. There are ‘internal’ and ‘external’ drives which are both fixed hard drives, i.e. rigid disks sealed into the drive unit, either within or attached to the computer. A third type of hard drive, known as ‘removable’, allows information to be recorded on ‘cartridges’, which can be removed and stored off-line for security purposes. These systems provide 80Mb to1 GB transportable cartridges, so if you can afford it, a removable drive gives you a great deal of extra storage capacity.

The development of optical technology has resulted in mass storage media such as CD-ROM drives and erasable optical disks. Optical storage devices give us immediate access to an enormous amount of information. Hundreds of megabytes of software, images, animation, and digitized sound can be recorded on one light, durable optical disk. Basically, there are three main types of optical disks: WORMs, CD-ROMs and erasable optical disks.

WORM stands for ‘write once, read many’. WORM disks are so called because they are indelible, i.e. they cannot be erased.  For this reason, they can last 100 years, and this technology is very useful for ‘permanent’ archiving of important documents in fields like medicine, law or history. Each WORM disk can hold one gigabyte of information.

CD-ROM system offers everything, from enormous shareware collections to large dictionaries, from multimedia databases to font families and graphics. Companies and government agencies have discovered that CD-ROM is the most economical way of sharing information. In fact, one CD-ROM disk (650 MB) can replace 300,000 pages of text (about 500 floppies), which represents a lot of saving in distributing materials and corporate databases. Yet CD-ROM technology has some disadvantages. You cannot write anything onto a CD-ROM disk, nor can you change what is imprinted on it. You can only ‘read’ it like a book. Another reason why CD-ROM is not widely used for ‘personal’ data storage is that CD-ROM drives are slow. They are fast enough for reading CD-ROM disks and audio CDs but are too slow when compared with hard drives.

Erasable optical disks usually hold between 120 and 1,000 MB of data in 3.5’’ or 5.25’’ disks. Unlike CD-ROMs and WORMs, erasable optical disks (EOD) are rewritable, i.e. we can write on them in the same way as a hard disk. They are mainly used as secondary storage devices, functioning as file servers or as a second storage unit, accompanying hard disks. EOD have two important advantages over hard disks: they are not affected by magnetic fields, and they have a longer data life. However, optical drives are slower than hard drives.

TOPICAL VOCABULARY

  1.  backing store                         хранение на внешних носителях                     
  2.  flexible                                  гибкий, подвижный
  3.  surface                                   поверхность
  4.  blank                                      пустой, чистый
  5.  spin                                        крутить(ся), вертеть(ся)
  6.  retrieve                                  восстанавливать, исправлять
  7.  rigid                                       жесткий, твердый, неподвижный
  8.  seal                                         запечатывать, герметически

                                                   закрывать

  1.  attach                                      прикреплять, прикладывать
  2.  erasable                                стирающийся
  3.  immediate                            немедленный, непосредственный,

                                                   прямой

  1.  durable                                 надежный, долговечный,

                                                   устойчивый

  1.  indelible                               нестираемый
  2.  permanent                            постоянный, неизменный
  3.  shareware                             условно-бесплатное ПО

                                                   («попробуй, перед тем как

                                                              купить»)

  1.  imprint                                  запечатлевать
  2.  secondary storage device      внешнее запоминающее

                                                    устройство

  1.  affect                                     воздействовать, влиять

EXERCISES

  1.  Read the introductory text and fill in the table.

Available types

Pros

Cons

Use/Purpose

Floppy disk

Hard disk

Optical disk

2. Compare these storage devices summing up the information of the table and using the following expressions:

Like…                                        Both…           

Unlike…                                    …is different to…

In comparison with…                …,whereas…

        In contrast to…                         …is similar to…                        

3. Read and translate the text. Before reading study the meaning of some abbreviations which you come across in the text.

SCSI (Small Computer System Interface) – интерфейс малых вычислительных систем

MB (megabyte) – мегабайт, Мбайт, Мб

SCA  (Single Connector Attach) – одноразъемный подключение

ID (Integrated Drive) – интегрированный накопитель

RPM (Rotations per minute) – оборотов  в минуту

ccd (concatenated disk) – сцепленный диск

  •  Make the list of unknown words and compare it with another student.

SCSI HARD DRIVES

As mentioned in the SCSI section, virtually all SCSI hard drives sold today are SCSI-2 compliant and thus will work fine as long as you connect them to a supported SCSI host adapter. Most problems people encounter are either due to badly designed cabling (cable too long, star topology, etc.), insufficient termination, or defective parts. However, there are a couple of things you may want to take into account before you purchase SCSI hard drives for your system.

Rotational speed: Rotational speeds of SCSI drives sold today range from around 4,500RPM to 15,000RPM. Most of them are either 7,200RPM or 10,000RPM, with 15,000RPM becoming affordable. Even though the 10,000RPM drives can generally transfer data faster, they run considerably hotter than their 7,200RPM counterparts. A large fraction of today's disk drive malfunctions are heat-related. If you do not have very good cooling in your PC case, you may want to stick with 7,200RPM or slower drives.

Note that newer drives, with higher areal recording densities, can deliver much more bits per rotation than older ones. Today's top-of-line 7,200RPM drives can sustain a throughput comparable to 10,000RPM drives of one or two model generations ago. The number to find on the spec sheet for bandwidth is ‘internal data (or transfer) rate’. It is usually in megabits/sec so divide it by 8 and you will get the rough approximation of how much megabytes/sec you can get out of the drive.

Obviously, the latest 15,000RPM drives and 10,000RPM drives can deliver more data than the latest 7,200RPM drives, so if absolute bandwidth is the necessity for your applications, you have little choice but to get the faster drives. Also, if you need low latency, faster drives are better; not only do they usually have lower average seek times, but also the rotational delay is one place where slow-spinning drives can never beat a faster one. (The average rotational latency is half the time it takes to rotate the drive once; thus, it is 2 milliseconds for 15,000RPM, 3ms for 10,000RPM drives, 4.2ms for 7,200RPM drives and 5.6ms for 5,400RPM drives.) Latency is seek time plus rotational delay. You can achieve similar or even better results by using the ccd (concatenated disk) driver to create a striped disk array out of multiple slower drives for comparable overall cost.

Make sure you have adequate air flow around the drive, especially if you are going to use a fast-spinning drive. You generally need at least 1/2'' (1.25cm) of spacing above and below a drive. See where the air flows in, and put the drive where it will have the largest volume of cool air flowing around it. You may need to seal some unwanted holes or add a new fan for effective cooling.

Another consideration is noise. Many 10,000 or faster drives generate a high-pitched whine which is quite unpleasant to most people. That, plus the extra fans often required for cooling, may make 10,000 or faster drives unsuitable for some office and home environments.

Form factor: Most SCSI drives sold today are of 3.5'' form factor. They come in two different heights”. 1.6'' (“half-height'') or 1'' (“low-profile''). The half-height drive is the same height as a CDROM drive. However, do not forget the spacing rule mentioned in the previous section. If you have three standard 3.5'' drive bays, you will not be able to put three half-height drives in there (without frying them, that is).

Interface: The majority of SCSI hard drives sold today are Ultra, Ultra-wide, or Ultra160 SCSI. The first Ultra320 host adapters and devices become available. The maximum bandwidth of Ultra SCSI is 20MB/sec, and Ultra-wide SCSI is 40MB/sec. Ultra160 can transfer 160MB/sec and Ultra320 can transfer 320MB/sec. There is no difference in max cable length between Ultra and Ultra-wide; however, the more devices you have on the same bus, the sooner you will start having bus integrity problems. Unless you have a well-designed disk enclosure, it is not easy to make more than 5 or 6 Ultra SCSI drives work on a single bus.

If you want to connect many disks, get wide or Ultra160 SCSI drives; they usually cost a little more but it may save you down the road.

There are two variant of wide SCSI drives; 68-pin and 80-pin SCA (Single Connector Attach). The SCA drives do not have a separate 4-pin power connector, and also read the SCSI ID settings through the 80-pin connector. If you are really serious about building a large storage system, get SCA drives and a good SCA enclosure (dual power supply with at least one extra fan). They are more electronically sound than 68-pin counterparts and they are easier to install too.

  •  Now read the sentences and say if they are true or false.

  1.  Fast drives need good ventilation system.
  2.  Fast drives have less rotational delay than slow-spin drives.
  3.  Cooling system is the only problem to take into account before you purchase fast drives.
  4.  3.5'' form factor is the only available form of SCSI hard drives.
  5.  It does not matter how many devices you have on the same bus.
  6.  All SCA drives  have a separate 4-pin power connector.

  •  Read the text again and sum up the information of the passages in the number of sentences given below.

Rotational speed: 1… 2… 3...4…5…

Form factor: 1…

Interface: 1…2…3…

LISTENING SKILLS

            

  •  Sue is in a shop. Listen to the conversation and  answer these questions.

  1.  What type of disks did Sue want to buy – hard or floppy?
  2.  Did she mention a particular make of disk?
  3.  What size disk did she ask for?
  4.  How much information can be held in the high density disks mentioned in the conversation?
  5.  How much was a pack of ten  high density disks?
  6.  How much did she pay altogether?

  •  Paul is interested in CD-ROMs. He has gone to his local computer shop to ask for some information.

Read the sentences below, and as you listen put a cross next to those which contain a technical mistake. Then listen again and rewrite these sentences with the correct information.

  1.  A CD-ROM disk is very different from a compact music disk.
  2.  You need a hard disk to read CD-ROM disks.
  3.  The data on a CD-ROM is read with a laser beam.
  4.  A typical CD-ROM disk can hold 100 MB.
  5.  The data on a CD-Rom can be changed or ‘written’ to.
  6.  A CD-ROM is a good way of storing large amounts of information (images, sounds, applications, etc.).
  7.  CD-ROM drives cannot play audio CDs.


DISCUSSION

                                             Working in pairs make up dialogues

                                     deciding which of the products would be most

                                     suitable for the purposes below. Discuss the pros and cons with a partner.

Products available

CD-ROM drive (each CD disk holds650 MB)

Removable cartridge drive (when you need additional storage you simply add another 45or 88 MB transportable hard disk enclosed in a plastic cartridge)

Hard disk drive (superfast 12ms hard  drive. Capacity ranges from 40 to 500 MB)

Erasable optical disk system (Rewritable 3.5’’floptical disks with a storage capacity of 128 MB)

DAT Data tape drive (digital audio tape drives to store computer data. Used for back-up purposes. Slow access. Huge amounts of information)

Problems to decide

  1.  To store data and programs at home.
  2.  To hold large amounts of information in a big company.
  3.  To store an illustrated encyclopedia for children.
  4.  To store historical records in the National Library.

Useful expressions

For personal use, I would recommend…because…

In a big company, it would be a good idea to…

However, …is good for an encyclopedia because…

Well, that depends on…

I agree/ disagree with you. CD-ROMs…

Besides, …

SUPPLEMENTARY READING

SEAGATE BARRACUDA 7200.7

                            Over the last three years, hardware enthusiasts have                        watched with increasing disappointment as Seagate took the respected Barracuda name and slapped it onto successive series of drives featuring more and more mundane performance. Though the Barracuda ATA IV and V featured impressively low noise floors, their performance trailed category leaders Western Digital and Hitachi by significant margins. A user purchasing a Barracuda ATA drive did so for its low noise, not its leading performance.

With the serial ATA 'Cuda V, Seagate finally debuted a drive featuring an 8-megabyte buffer as well as the only drive to eschew a PATA-to-SATA bridge. While this first attempt exhibited some improvement over the standard parallel ATA (2-meg) unit, the SATA Barracuda nonetheless trailed WD's and Hitachi's disks by a significant margin.

In a fashion that surprised some watchers, Seagate quickly followed up on the Barracuda ATA V with the Barracuda 7200.7. The former series, with its 60 gigabyte platters, represented somewhat of a transitional product as Seagate ramped up production of units with 80 GB platters, a size regarded as more "standard" by the industry.

The Barracuda 7200.7 family delivers a somewhat confusing array of varying configurations. All feature 80 gigabytes per platter and specified 8.5 millisecond random read seek times. The standard ATA-100 units, available in sizes from 40 GB to the flagship 160 GB, come with a 2-megabyte cache. The ATA-100 "Barracuda 7200.7 Plus" comprises 120 GB and 160 GB models with 8-megabyte buffers. Finally, serial ATA versions spanning 80 GB to 160 GB come standard with 8 megabytes. Notably absent on the 7200.7 is the "SeaShield," a metal plate found on earlier models that protected electronics mounted along the underside printed circuit board. Keep in mind that the SATA 7200.7 does not feature a traditional 4-pin molex power connector but rather requires the new L-shaped SATA power connector either incorporated on the power supply (rare) or through an adapter (found in some retail SATA controller kits).

FINAL TEST

  •  Put the following sentences in the  same  

                                  sequence  as the information is arranged in the 

                                  introductory text (Расположите следующие

                                  предложения в той же последовательности, в какой информация представлена в вводном тексте)

1.  A. EOD have some advantages over hard disks.

  1.  Floppy disks are divided into tracks and sectors for storing information.
  2.  WORM disks are suitable for storing archives.

        D. Hard disks are faster than floppies.

  •  Which sentence can be used in the annotation to the text «SCSI hard drive» (Какое предложение может быть использовано в аннотации к тексту)

2. A. Rotational speed, form factor and interface should be taken into account in using SCSI hard drives.

  1.  The text gives valuable information on the factors mostly important in using SCSI hard drives.
  2.  The text sum up the information about SCSI hard drives.

  •  Give the right English equivalent to the following Russian sentence (Дайте верный английский эквивалент русскому предложению)

Убедитесь, что ваш дисковод установлен в том месте, где он получает достаточное охлаждение.

3. A. Make sure you have adequate air flow around the drive, especially if you are going to use a fast-spinning drive.

  1.  See where the air flows in, and put the drive where it will have the largest volume of cool air flowing around it. Make sure your drive is situated so that it has adequate volume of cool air flowing around it.

  •  Give the right Russian equivalent to the following English sentence (Дайте верный русский эквивалент английскому предложению)

Note that newer drives, with higher areal recording densities, can deliver much more bits per rotation than older ones. 

4. A. Обратите внимание, что новые дисководы с увеличенной записывающей способностью могут обрабатывать намного больше битов за вращение, чем старые дисководы.

    В. Помните, что усовершенствованные дисководы имеют увеличенную записывающую плотность и могут поставлять больше битов за вращение, чем старые дисководы.

    С. Обратите внимание, что старые дисководы могли обрабатывать больше битов за вращение, чем новые с увеличенной записывающей способностью.

  •  Find the equivalents in two languages (Найдите эквиваленты в двух языках)

5. immediate                   А.  стирающийся

6. indelible                      В.   гибкий 

7 rigid                              С.  неизменный   

8. durable                         D. жесткий    

9. permanent                          E. нестираемый                 

10. flexible                       F. надежный

11. erasable                      G. немедленный

                                        H. легкий

  •  Complete the sentences with the proper word (Закончите предложения подходящим по смыслу словом)

12. Hard or floppy disks are used for permanent …….

13. Tracks and sectors are marked on the floppy disk …….

14. The monitor is controlled by a separate circuit board, known as ………

15. Some software which is free of charge (‘try before buy’) is called…….

16. Disks without any record are  ……...

17.  WORM stands for ……….

18.  If we can write different information on disks again and again they are called ………….

  •  Choose the right variant (Выберете правильный вариант)

19. When data are incorrect the user should  …….. them.

A. Input                                      B. Retrieve

C. Attach                                    D. Store

20. The user can’t change what is ….. on WORM disks.                                  

A. Imprinted                                B. Read

C. Sealed                                     D. Spinned

21. Hard disks are …….. by magnetic fields.

A. Written                                    B. Attached

C. Affected                                   D. Surrounded

22. If the hard disk is considered ‘internal’, it means that it is ……into the computer.

A. Attached                                   B. Sealed

C. Imprinted                                  D. Spinned

23. CD-ROM drives are …….. then hard drives.

A. Faster                                        B. Slower

24. Floppy and hard types of disks work …...

A. In the same way                           B. In quite different ways

C. Slightly different                          

25. Erasable optical disks are mainly used as ……..

A. Secondary storage devices            B. Backing store                         


 

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