FAT32 File System

Learning data recovery familiar with file system structure is the premise, first understand the next FAT32 file system structure.

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A . DBR Fan Area

FAT32 the main byte meaning of the DBR sector.

1. Number of bytes per sector

2. Number of sectors per cluster

3. number of reserved sectors

4. number of FAT tables

5. File System size (number of sectors)

6. size per FAT Table (number of sectors)

7. root directory initial cluster number

FAT32 boot Sector structure

byte offset ( in binary)	Byte data	Meaning
00-02	3	Assemble the instructions, jump to the boot code.
03-0a	8	OEM version
0b-0c	2	512
0D	1	Number of sectors per cluster, this value is 2 integer power max not exceeding
10	1	the number of FAT tables, usually 2
11-12	2	fat32 This value is not set to 0
13-14	2	Total sectors, small fish 32 use offset 0x20-0x23
16-17	2	Size sector data per FAT (fat16/12 use),FAT32 not here
18-19	2	Number of sectors per track

1a-1b	2	Number of heads
1c-1f	4	The number of sectors that have been used by the partition, as well as the number of sectors, which refers to the sector offset of the DBR relative to the disk 0 sector
20-23	4	Total File System sectors
24-27	4	Number of sectors per FAT table size (FAT32 dedicated)
28-29	2	Tag, if 1 indicates that only one fat table is active, otherwise two servings of fat mirror each other
2a-2b	2	Version number
2c-2f	4	Root directory start cluster number
1fe-1ff	2	Signature "55AA"

The emphasis on the background marker needs to be noted.

A FAT32 DBR Sector example is used to analyze

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0x00-0x02:3 bytes, jump instruction.

0x03-0x0a:8 bytes OEM version number MSWIN4.1

0x0b-0x0c:2 bytes, number of bytes per sector (0x0200)

0x0D :1 bytes, each sector number (0x10)

0x0e-0x0f:2 bytes, reserved sector number,(0x0020), That means FAT1 starts with the sector.

0x10:1 the number of FAT tables in bytes.

0x11-0x14:4 bytes,FAT32 not used for 0

0x15:1 bytes , Media descriptor , 0xF8 = local hard drive (not allowed)

0x16-0x17:2 bytes,FAT32 do not use this value of 0

0x18-0x19:2 bytes , number of sectors per track , (0x003f)

0x1a-0x1b:2 -byte head count,255(0x00ff)

0x1c-0x1f:4 Bytes, number of sectors used before partitioning , 1142528 (0x00116f00)

0x20-0x23:4 Bytes, file system Size sector number 29167872 (0x01db1100)

0x24-0x27:4 bytes,FAT table sector number 14240 (0x000037a0)

0x2c-0x2f:4 Bytes, root cluster number 2(0x00000002)

0x1fe-0x1ff:2 bytes , signature "55AA"

This article is from the "Lin Feng Data Recovery" blog, so be sure to keep this source http://shujvhuifu.blog.51cto.com/10412640/1661960

FAT32 File System