Difference between Transfer Time and Disk Access Time in Disk Scheduling

1. Transfer Time : Time required to transfer the required amount of data. It can be calculated by the given formula
```Transfer time,
= Data to be transfer / transfer rate ```
Data to be transfer is given in the question and transfer rate is sometimes given and sometimes it may not be given. It can be calculated by the given formula.
```Transfer Rate,
= {(Number of heads or number of surfaces in the disk)
*(capacity of one track or number of sectors in each track)
*(Number of rotations in each track to reach the required sector)}```
2. Data Access Time: It is the total time required to access the data.It means total time required to read/write the data from the disk. Following is the formula to calculated the data access time:
```Data access time,
= {(Seek time) + (Rotational Latency) + (Data Transfer Time)} ```
Note:
• Seek time – The time required by R/W head to move to the desired track from the current position.
• Rotational Latency – Time required by sector to come under R/W head.
Difference between Transfer Time and Disk Access Time in Disk Scheduling :
sr.no. DATA TRANSFER TIME DATA ACCESS TIME
1 Time required to transfer the required amount of data. It is the total time required to access the data.It means total time required to read/write the data from the disk.
2 To calculate data transfer time we require only transfer rate to calculate data access time we require seek time, rotational latency and data transfer time
3 Thus to calculate data transfer time there is no requirement of data access time To calculate data access time there is the requirement of data transfer time
4 Transfer time=Data to be transfer/transfer rate Data access time = {(Seek time) + (Rotational Latency) + (Data Transfer Time)}

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