file system , modern operating system , 3rd edition

Windows NT/2000/XP/VISTA supports NTFS(native file system),while MS-DOS/Windows95/98
supports FAT

contiguous file allocation:CD-ROM
Lined-List Allocation
Linked-List Allocation using a Table In Memory:FAT(the disadvantage is that the table must be kept in main memory all the time, and the table is large, so waiste the memory)
I-nodes:the i-nodes need be in memory only when the corresponding files are open.
Log-Structured FS:i-nodes still exist but are scattered all over the disk.so a i-node map is introduced(not widely used).
Journaling File System:NTFS,ext3
encompass(包含)
Virtual FS(UNIX uses it):  unified interface for all the different FS,especially for NFS
FAT-32:widely used in embedded digital devices


打开一个文件：根据路径找到superblock，再找到根目录，沿着目录树找到directory entry（可能会HASH），从directory entry找到i-node载入内存,将其添加到系统范围的打开文件表和进程的打开文件表，i-node里是属性和指针，指向disk-block，打开操作的返回值是一个指针（文件描述符），指向进程的打开文件表中的那个条目。