What Restrictions Must Such Systems Impose?

963 Words4 Pages
OperatingSystems
COEN-283
FALL2016

Assignment5-FileSystems&I/O

1. Isthe“open”systemcallinUNIXabsolutelyessential?Whatwouldbetheconsequences of not having it?
Ans :-
- If there is no “Open” system call then for every read operation we have to specify the name of the file to be accessed.
- The system would have to fetch the i-Node for it, although it could be cached
- In this situation one issue may arise which is when to flush the iNode back to disk. That can be done by timeout, but it would be clumsy.
- Overall, it may work but with much more overhead involved

2. In some systems it is possible to map part of a file into memory. What restrictions must such systems impose? How is this partial mapping implemented?

Ans :-

-It is possible to map part of a file into memory instead of entire file. But in this situation,
A part of file which needs to be mapped is required to begin from a page boundary.
-Hence a restriction on such system is that the pages should have a length of an integral number.
-Each mapped page uses the file itself as a backing store. Unmapped memory uses a scratch file or partition as backing store.

3. Name one advantage of hard links over symbolic links and one advantage of symbolic links over hard links.

Ans :-

Advantage of Hard links over Symbolic links :
- Hard link contains direct reference to the object. Hence it is faster, whereas symbolic link contains a path name to the object which must be resolved to find the object.
- Hard links do not

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