What about file systems-1st a wide variety of file systems

What is a file system, and how can a file system be classified? This is the question to be discussed in this article.
The file system [I] stores and organizes the data contained in computer files and files, so as to conveniently find and access them. More formally, a file system is a collection of abstract data types (such as metadata) used for storage, hierarchical management, processing, navigation, and data access and recovery.
 
This article [ii] compares many common file systems in various aspects.
 
File systems can be divided into disk file systems, network file systems, and special purpose file systems. Further, you can use the following concepts to differentiate the concepts of file systems.
 
1.1 Disk File System
A disk file system is a file system designed to store data in a storage such as a disk. Memory is directly or indirectly connected to the computer. Some disk file systems use the journaling file system or versioning file system ).
 
A version file system is different from a log file system. A version file system allows multiple versions of a file at the same time. Therefore, it is a form of version control. In most versions, the file system saves multiple old copies of files. Some version file systems limit the number of modifications per minute or hour to prevent large volumes of trivial changes from being stored. In addition, the file system periodically collects snapshots, And the snapshot content can be accessed as normal files.
 
1.2 flash File System
A flash file system is a file system designed to store data on flash. With the increasing popularity of mobile devices and the increasing expansion of flash memory capacity, Flash file systems have become more common.
 
Although the disk file system can be used on flash, this method has many defects due to the different features of flash and disk. For example, the entire flash memory needs to be erased during rewriting, which is a time-consuming operation. Therefore, it is helpful to perform the erasure operation only when the memory is idle. Another difference between flash memory and disks is that the mechanical movement of the disk's mobile head can be optimized to reduce the seek time, but the flash memory can be randomly accessed and the seek time can be ignored. In addition, flash memory has a limit on the number of writes. If a block in flash memory is overwritten multiple times, it may seriously affect its usage time, therefore, the Flash file system needs to be designed to have a uniform write count for each storage block.
 
Log File systems such as JFFS2 and YAFFS have many features required by Flash file systems.
 
1.3 Database File System
A new concept of file management is database-based file systems. As an alternative or supplement to hierarchical structured management, database-based file systems use features such as file types, themes, authors, and similar metadata to identify files.
 
1.4 transaction File System
In the operating system, transactions have atomicity, that is, either all or all features. In the file system, some operations also have the characteristics of things. In these operations, you need to change the structure of multiple files and disks. These changes are relevant and need to be executed at the same time.
 
Transactional file system ensures that these operations are completed or completely restored. This means that when the system crashes or powers down, the storage status will be consistent after recovery.
 
A log file system is one of the technologies that can be used to introduce transaction-level consistency in the file system structure.
 
1.5 Network File System
A Network File System is a remote file access protocol that provides users with the ability to access files on servers.
 
NFS, AFS, SMB, and other protocols are typical network file systems.
 
1.6 shared Disk File System
In the shared disk file system, multiple machines (usually servers) access the same external disk subsystem. The file system arbitrates access to the storage subsystem to prevent write conflicts.
 
Redhat GFS and ibm gpfs are shared disk file systems.
 
1.7 special purpose file systems
A file system that is not a disk file system or a Network file system can be called a special purpose file system (special purpose file system ).
 
This article is welcome to reprint, please keep the original blog link http://blog.csdn.net/fsdev/article
 
[I] http://en.wikipedia.org/wiki/File_system
 
[Ii] http://en.wikipedia.org/wiki/Comparison_of_file_systems