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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