Lightweight Building Blocks

In the last article we looked in depth at the heart of the computer construction:

• The CPU (processor)


• Memory (RAM)


• The motherboard (main board)

Now we'll watch the rest of the PC:

• The storage subsystem (hard disk or hard drive)


• The graphics processor (GPU)


• Case


• The cooling (HSF or radiator and fan)

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The storage (hard drives)

When you save your work, run an application or game, a stream or encode to disk or otherwise need to access or permanent storage of your disk subsystem offers are limited by its performance. The storage system is almost the only mechanical system in the computer (although this is changing with the advent of Solid State Drives, SSD). The data is stored on a magnetic hard disk and arranged in concentric circles around the disc from the center to the periphery. Therefore, if your computer needs to access data at one end of the disc, then the other, the reader must physically move the head from front to back, and wait for the disks around to the right place begin the process of reading or writing. The time taken to do this is known as latency, and mean time to move the head at some point and read data are given as Average Seek Time (usually in milliseconds, ms).

Manufacturers provide the spin speed and the average data for time with their readers. In addition, all drives have a cache memory onboard the software uses to store smart player before (or read ahead) requests for reading so that it can intelligently preempt almost get the data you want to read . The data can then be recovered quickly without requiring the drive to move the head. The other important factor in disk performance is to have such a large pipe possible (eg bandwidth) between the player and the CPU to ensure that once the drive has data available, it can be transferred.

Our design requirements for the storage of good performances are, in roughly this order:

• Broadband - made with;
  
  
  
  
  • high surface density (more data packed into a smaller space can be read quickly, the target density around 300 gigabits per square inch)
  
  
  • a high drive speed of at least 7500rpm or better yet 10,000 or more inhabitants
  
  
  • High speed data transfer 3Gb / s,
  
  
  • and support the latest standards Interface SATA-II or SCSI (SAS)
  
  
  • a large cache on board at least 16 MB and 32 MB or more better
  
  
  
  
  


• best positioning time (which should be under 10ms, under 5 ms for random access performance extremes)


• RAID (Redundant Array of Economic discs) - using arrays of disks working in parallel to achieve higher speeds, transfer rates and higher redundancy of resilience in the unlikely event of a disk failure

Most manufacturers of consumer PCs that will give you disk capacity in Great Britain, which is used as a selling point, they are often unable to give you the above data and are unlikely the having taken into account in the design. There is a balance between performance and value, but also a delicate balance between bandwidth and seek times. If the work you do is mainly sequential disk access, it is probably more important to have a high bandwidth and rapid search time (ie, photography, multimedia). You might also consider when designing storage arrays RAID impact on the average seek, write speeds and have their own configuration settings that affect the effectiveness reviews of their work.