I'm reading Operating System Concepts by Avi Silberschatz(9thE), in chapter 11 File-System Interface, when the author explains the concepts of file, he states that

The information about all files is kept in the directory structure, which also resides on secondary storage. Typically, a directory entry consists of the file’s name and its unique identifier.

I think the directory structure that holds the information of all files is of critical importance, which the author does not extend in depth though. I don't even know the terminology for this concept of directory structure. It should be somewhere on the disk and well maintained. Could anyone clarify it for me? Any literature and links will be appreciated.

Thanks in advance!


1 Answer 1


Your intuition is mostly correct. I believe the description is not really sufficient. Directory entry should at least be able to allow the OS to be able to locate some parts the file on disk for I/O operations. File System is divided into some fixed size partitions of available space ranging from 1-16KB. For efficient implementations a file is not necessarily written in contiguous blocks therefore the challenge is mostly having an efficient way of determining which blocks belong to which file without giving up on too much space and being efficient at the same time. Similarly other meta information should also be kept such as user permissions, hard links and so forth.

Currently Unix inode system is an efficient implementation. An other example would be maintaining a FAT (File Allocation Table) which is less efficient. I believe reading about Inodes would be great place to start.


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