Question

What will the storage capacity of a disk of
2.5 inch diameter 8 plates (16 recording
surfaces) with 512 sectors per track and
2048 tracks per recording surface ? Assume
that one sector can store 1048 bytes of
data.

Answer 1

Explanation:

Given:

Disk  = 8 platters * 2 Surfaces =16 platters

each platter = 4084 tracks

each track =  400 sectors

each sector = 1 MB

Calculate:

one track = 400 sectors

= 400 * 1 MB

= 400 MB

one platter = 4084 tracks

= 4084 * 400 MB

= 4 *1024 * 400  MB

= 4 * 400 * 1024 MB

= 4 * 400 GB

= 1600 GB

16 platters = 16 * 1600 GB

= 25600 GB

= 25 * 1024 GB

= 25 TB

The storage capacity of this disk in Bytes = 25 TB

Given:

Disk Rotation Speed = 6000 rpm

Average seek time = 10 millisecond

 

Sample Convertion is Shown Below:



Rotational latency = Average seek time + Average Rotational delay + Controller Overheads

 

Average seek time = 2 millisecond (given)

 

Calculate

Average Rotational delay = ½ Time of Rotation in milliseconds

 

Average Rotational delay = ½ * (60/6000) *1000 millisecond

= ½ * 10 millisecond

= 5 millisecond

Rotational latency = Average seek time + Average Rotational delay 

Rotational latency = 2 millisecond + 5 millisecond

= 2 + 5 millisecond

= 7 millisecond.

Answer 2

The storage capacity of 2.5-inch disk is approximately equal to 16TB.

Given:

• 2.5-inch Disk with 8 plates.
• 2048 tracks per recording surface.
• 512 sectors per track.
• 1048 bytes of data stored in one sector.

To find: Storage capacity of disk.

Step by step explanation:

Step 1:

Total number of recording surfaces = number of plates * 2.
(∵ data can be stored both in upward and downward direction of plater.)
Total number of recording surfaces = 8 * 2 = 16

Step 2:

Total number of tracks in the disk = Number of recording surfaces * number of tracks per recording surface.
Total number of tracks = 16 * 2048 = 32768

Step 3:

Total number of sectors on the disk = Total number of tracks * Total number of sectors per track.
Total number of sectors = 32768 * 512 = 16777216.

Step 4:

Total amount of data stored on the disk = Total number of sectors * Total amount of data stored in each sector.
Total amount of data stored = 16777216 * 1048 = 17582522368 bytes.
Total amount of data stored = 17582522368/1024
                                               = 17170432 MB
                                               = 17170432/1024
                                               = 16768 GB
                                               = 16768/1024
                                               = 16.375 ≈ 16TB

The storage capacity of 2.5-inch disk is approximately equal to 16TB.

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