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

9. attach прикреплять, прикладывать

10. erasable стирающийся

11. immediate немедленный, непосредственный,

прямой

12. durable надежный, долговечный,

устойчивый

13. indelible нестираемый

14. permanent постоянный, неизменный

15. shareware условно-бесплатное ПО

(«попробуй, перед тем как

купить»)

16. imprint запечатлевать

17. secondary storage device внешнее запоминающее

устройство

18. 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…