Spooling and Buffering in Operating System:
Definition and Explanation:
Spooling in Operating System:
The technique of buffering is not sufficient for non-sharable devices. For example all process output ting a document to a printer would be suspended while one process controls the printer. A print job can even last 30 minutes and this is dearly not acceptable to leave processes suspended for such a long time. To overcome this difficulty a technique called spooling is used. It stands for Simultaneously Peripheral Operations Online.
Spooling involves all processes directing any output data to an un-sharable device to a component of the I/O management module called the spooler.
Function of Spooler:
The main functions of Spooler are the following:
- On receiving output data, it stores it on hard disk and enters the job in a spool queue.
- When the un-sharable device become available it picks the first job from the queue and transfers its data from the hard disk to the un-sharable device.
- Note that jobs in spool queue can be prioritized.
Advantages of Spooling:
The advantages of spooling are as follows:
- Processes are not suspended for a long time.
- It can produce multiple copies of the output without running the process again.
Disadvantages of Spooling:
The disadvantages of spooling are as follows:
- Need large amounts of disk space.
- Increase disk traffic.
- Not practical for real-time environment, because results are produce at a later time.
