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(CHECK SLIDESHOW)

Representation of File Directory

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Directed Acyclic Structure

Implementation of File Directory

Besides name, data, and metadata, the filesystem must track:

• Size
• Type
• Location
• Protection
• Use

File Control Block

Where to store this is an important design issue.

• If you store attributes directly, you could slow down the search.

File Control Block: Data structure that encapsulates are relevant attributes of a process.

• Stored separately from the file directores
• Tradeoff: Store critical attributes in the directory, but have other attributes in the FCB via pointer.

TODO There are three approaches

1. Fixed-Size Array of ???
   • Limited size.
   • Random-access (fast search).
2. Variable-Length Array of ???
   • ???
3. Variable-Length Array of ???
   • ???

Internal Structure

Operations on Files

Open a File

Open File Table: Data structure that tracks all files currently in use.

• Allows for efficient access.

Open File Operation: Prepares a file for efficient access by TODO

Whenever you update a file, you never update just a block. Everything wr.t. the file in memory has to be erased and re-added.