Chapter 14 - File System Implementation

Resides on secondary storage.

Provides efficient and convenient access to disk and by allowing data to be stored, located and retrieved easily

• Basic File System

• File Control Block

• File System

• File Organization Module

Storage Structure consisting of information about a file

-inode #

-file dates

-file owner

-file size

-file data blocks or pointers to file data blocks

• File System

• Basic File System

• File Organization Module

• File Control Block

Manage I/O devices at the I/O layer

Give command like "read drive 1"

• Device Drivers

• Basic File System

• Logical Devices

• Devices

Manage memory buffers and caches (Allocation, freeing, replacement)

Given command like "retrieve block 123" translates to device driver

• Basic File System

• File Organization Module

• Logical File System

• File System

Understands files, logical address, and physical blocks

-translates logical block # to physical block #

-Manages free space, disk allocation

• Logical File System

• Basic File System

• File Organization Module

• File Control Block

Manages metadata information.

Translates file name into file number, file handle, location by maintaining file control blocks

• Logical File System

• File System

• File Block System

• Basic File System

Uses the same page cache to cache both memory-mapped pages and ordinary file system I/O to avoid double caching data.

• Unified Buffer Cache

• Page Cache

• Buffer Cache

Caches pages rather than disk blocks using virtual memory techniques and addresses.

• Unified Buffer Cache

• Page Cache

• Buffer Cache

A separate section of main memory for frequently used blocks.

• Unified Buffer Cache

• Page Cache

• Buffer Cache

Each file has its own index block(s) of pointers to its data blocks.

• Linked Allocation

• Indexed Allocation

• Contiguous Allocation