张柏礼东南大学计算机学院操作系统概念.ppt

11.1 Structure
Most OS support more than one Structure
Windows:
FAT ( Table) (FAT, FAT32) NTFS (Windows NT ) CD-ROM，floppy-disk
sector 10
11.1 Structure
4）I/O control
consists of device drivers and interrupt handlers to transfer information between the main memory and the disk system.
I/O transfers between memory and disk are performed in blocks not in bytes
Each block has one or more sectors Sector usually are 512 bytes
11.1 Structure
To discuss block allocation and free-block algorithms and trade-offs
11. Implementation
11.1 Structure 11.2 Implementation 11.3 Directory Implementation 11.4 Allocation Methods 11.5 Free-Space Management 11.6 Efficiency and Performance 11.7 Recovery 11.8 Log-Structure
OPERATING SYSTEM CONCEPTS
操作系统概念-11
张柏礼
11. Implementation Objectives
To describe the details of implementing local and directory structures
To describe the implementation of remote
11.1 Structure organized into layers
11.1 Structure
1）The logical
manages metadata information (all the FS structure except the actual data)
▪ To manage the directory structure ▪ To manage the via FCB
▪ FCB: file control blocks
▪ Contains information such as ownership, permissions, location of the
▪ Responsible for protection and security.
11.1 Structure
▪ Each file’s logical block addresses are numbered from 0 (or 1) through N.
▪ Each file’s physical block addresses are different, are unique within a partition.
Free-space manager:
11.1 Structure
3）Basic
issues generic commands to the appropriate device driver to read and write physical blocks on the disk
Input: retrieve block 123 Output: retrieve drive 1, cylinder 73, head 2,
11.1 Structure Disks provide the bulk of secondary storage
on which a is maintained
Disks can be written in place (原地修改)
Sequential access and direct access
2）The module
knows about the files and their logical blocks, as well as physical blocks.
To translate a file’s logical block addresses to its physical block addresses.
resides on secondary storage (disks)
It provides efficient and convenient access to disk by allowing data to be stored, located, retrieved easily
It poses tw define how the should look to the user
▪ How to define a its attributes, the operations, the directory structure
To create algorithms and data structures to map the logical onto the physical secondary-storage devices.
A device driver can be regarded for a translator ▪ Input: retrieve drive 1, cylinder 73,head 2, sector 10
▪ Output: low-level, hardware-specific
instructions that are used by the hardware