Disk capacity refers to the amount of data storage space available on a computer's hard disk drive (HDD). The document discusses HDD components like platters, spindles, and read/write arms that enable data storage. It provides an example calculation of disk capacity based on number of surfaces, sectors, tracks, and bytes. Larger disk capacity allows more data storage but relies on moving parts and consumes more power than alternatives.

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Disk Capacity

2. Contents
What is Disk Capacity?
Components of HDD
Disk Capacity Calculation
Advantages of Disk Capacity
Disadvantages of Disk Capacity
Summary of Disk Capacity
Reference in Subject
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3. What is Disk Capacity?
•Disk capacity refers to how much disk space one or
more storage devices provides
•It measures how much data a computer system may contain.
Example :
1. computer with a 500GB hard drive has a storage capacity of
500 gigabytes.
2. A network server with four 1TB drives, has a storage capacity
of 4 terabytes.
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4. Now you can see Graphically Disk Capacity
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5. HDD PHYSICAL COMPONETS
1 .Platters :
• The platters are the circular discs inside the hard drive where the 1s and 0s that
make up your files are stored.
• Platters are made out of aluminum, glass or ceramic and have a magnetic
surface in order to permanently store data.
• On larger hard drives, several platters are used to increase the overall capacity
of the drive.
• Data is stored on the platters in tracks, sectors and cylinders to keep it
organized and easier to find.
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6. 2. The Spindle :
• The spindle keeps the platters in position and rotates them as required.
• The revolutions-per-minute rating determines how fast data can be written to
and read from the hard drive.
• A typical internal desktop drive runs at 7,200 RPM, though faster and slower
speeds are available.
• The spindle keeps the platters at a fixed distance apart from each other to
enable the read/write arm to gain access.
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HDD PHYSICAL COMPONETS con…

7. 3. The Read/Write Arm :
• The read/write arm controls the movement of the read/write heads, which do
the actual reading and writing on the disk platters by converting the magnetic
surface into an electric current.
• The arm makes sure the heads are in the right position based on the data that
needs to be accessed or written; it's also known as the head arm or actuator
arm.
• There is typically one read/write head for every platter side, which floats 3 to
20 millionths of an inch above the platter surface.
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HDD PHYSICAL COMPONETS con…

8. 4. Actuator :
• The actuator or head actuator is a small motor that takes instructions
from the drive's circuit board to control the movement of the
read/write arm and supervise the transfer of data to and from the
platters.
• It's responsible for ensuring the read/write heads are in exactly the
right place at all times.
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HDD PHYSICAL COMPONETS con…

9. DISK CAPACITY CALCULATION
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• Consider a disk with the following characteristics:
Number of surface 16
Number of sectors / cylinder 4096
Number of tracks per surface 2048
Number of bytes per sector 512
1) How many patters does the disk have ?
2) How many sectors per track ?
3) What is the total size of this disk

10. Answers
1 . I got: number of surfaces / 2 = 8
2. Number of sectors per track = no of sectors per cylinder/16 ie,
4096/16 = 256
3. Total storage =
16(surface)*256(sector)*2048(cylinder)*512(bytes) = 4GB
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11. ADVANTAGES of DISK CAPACITY
1. Large capacity
2. Faster than optical disks like DVD'S
3. Persistent storage
4. Easily replaced and upgraded
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12. DISADVANTAGES of DISK CAPACITY
1. Relies on moving parts
2. Disk surface can be damaged
3. Heavy power consumption
4. Noisy
5. Slower read and write speed than RAM
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13. SUMMARY
• Disk Capacity or Disk Spacing or Disk Storage Same words.
• Now You can find HDD components function and identify easily.
• Able to how to calculate of Disk Capacity.
• Can you describe of advantages and disadvantages
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