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file system

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File management system in operating system
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This entry is made by Compilation and application of scientific encyclopedia entries of "Science Popularization China" to examine.
The file system is the operating system used to define storage device (Disk is common, and NAND Flash based Solid state hard disk ）Or files on the partition data structure ； That is, the method of organizing files on the storage device. Responsible for management and Storage file The software organization of information is called Document management system , referred to as file system. The file system consists of three parts: the interface of the file system, the software collection for manipulating and managing objects, and objects and attributes. From a system perspective, the file system is responsible for organizing and allocating the space of file storage devices, storing files, protecting and retrieval System. Specifically, it is responsible for creating files for users, storing, reading, modifying, and dumping files, Control documents The user can cancel the file when it is no longer used.
Chinese name
file system
Foreign name
file system
Category
operating system
Purpose
To manage space

catalog

  1. one brief introduction
  2. two function
  3. three code
  4. four FAT
  5. five NTFS
  6. six CDFS
  7. seven exFAT
  1. eight RAW
  2. nine Ext
  3. ▪ Ext2
  4. ▪ Ext3
  5. ▪ Ext4
  6. ten Btrfs
  7. eleven ZFS
  8. twelve HFS
  1. ▪ HFS file system concept
  2. ▪ HFS file system development process
  3. ▪ framework
  4. thirteen HFS+
  5. fourteen ReiserFS
  6. fifteen JFS
  7. sixteen VMFS
  1. seventeen XFS
  2. eighteen UFS
  3. nineteen VXFS
  4. twenty ReFS
  5. twenty-one WBFS
  6. twenty-two PFS

brief introduction

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In the computer, the file system is the system that names files and places files for logical storage and recovery. DOS 、Windows、 OS/2 、 Mac Both the intosh and UNIX based operating systems have file systems in which files are placed somewhere in a hierarchical (tree) structure. Files are placed in a directory (a folder in Windows) or Subdirectory , on Tree structure In the position you want.
File system Specifies the rules for naming files. These rules include the maximum number of characters in the file name, which characters can be used, and File name suffix It can be long. The file system also includes directory structure Find the format of the specified path of the file. [1]
File system is software system The existence of this part makes it easy for applications to use abstract named data object And variable size space.

function

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Structure diagram
The file system is the method and data structure used by the operating system to define the files on the disk or partition; That is, the method of organizing files on disk. Also used for Storage file The type of disk or partition, or file system. Therefore, it can be said that "I have two file systems" means that it has two partitions, one for storing files, or other“ Extended File System ", which means the type of file system.
It is important that the disk or partition is different from the file system it contains. A few programs (including the most reasonable programs that generate file systems) directly a sector Operation; This may damage an existing file system. Most programs operate based on file systems and cannot work on different file systems.
Before a partition or disk is used as a file system, it needs to be initialized and the record data structure written to the disk. This process is called file system establishment.
Most UNIX file system types have similar general structures, even if the details change. Its central concept is super block, i node inode , data block data block， Directory block and indirect block. The super block includes the overall information of the file system, such as the size (its accurate information depends on the file system). The i node includes all the information of a file except the name. The name and the number of i nodes exist in the directory together. The directory entry includes the file name and the number of i nodes of the file. The i node includes the number of several data blocks for storing the data of the file. There is only a small amount of data block space in node i. If more data blocks are needed Dynamic allocation Pointing to the data block Pointer Space. These dynamically allocated blocks are indirect blocks; To find data block The name indicates that it must first find the number of the indirect block.
UNIX file systems usually allow holes to be created in files, which means that the file system pretends that there is a special location in the file, only 0 bytes, but does not reserve the actual disk space 。 This pair of small ones [2] Binary file Frequently, Linux Shared library , some databases and other special cases.
Holes are useful. In the author's system, a simple Measuring tools It shows that in the 200MB disk space used, about 4MB is saved due to the holes. In this system, there are relatively few programs [3] Database file 。
file Functions of the system Including: management and scheduling of files storage space , providing documentation Logical structure 、 Physical structure And storage method; Implementation file from ID to Physical address To realize the control operation and access operation of files, realize the sharing of file information and provide reliable Document confidentiality And protective measures Safety measures 。
The logical structure of the file is based on the content of the file logical relationship Organize the file structure. The logical structure of files can be divided into streaming files and recording files.
Streaming file: the data in the file is a string Character stream , no structure.
Record file: several Logical record Each record is composed of the same data item Composition. The length of data items can be determined or uncertain.
Main defects: poor data correlation, inconsistent data, redundancy.

code

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The following is the file system code, according to which we can better understand the file system Workflow
  1. one
    main.cpp
#include"blockinodesuperblock.h" //----------------------- intmain() { control.open("control.txt", ios::in|ios::out|ios::nocreate); inti; control>>i; control.close(); if(i!= 0)//Initialize if it is not 0 { initial(); } control.open("control.txt", ios::in|ios::out|ios::nocreate); control.seekp(0); Control<<0;//The default is to continue on the basis of the last time without further initialization control.close(); strcpy(curname,"root");// The current directory file name is root road[0]=0;// Current directory path (store the node number from the root directory to here) Num=1;//The last road [num-1] is the node number of the current directory file i Cout<<"Please log in to the system n"; while(! Login ()//until login cout<<"wrong!!! \n"; cout<<"loginsuccess"<<endl; cout<<"******Welcome"<<auser<<"******"; readsuper(); getcommand();// Command parsing function writesuper(); return0; }
blockinodesuperblock.h
Intialloc()//Requesting an i node returns the node number, otherwise - 1 is returned { if(superblock.fiptr>0) { inttemp=superblock.fistack[80-superblock.fiptr];// Currently available superblock.fistack[80-superblock.fiptr]=-1; superblock.fiptr--; returntemp; } return-1; } //---------------------- Void tree (int index)//Specify a node number and recycle an i node { Disk. open ("disk. txt", ios:: in | ios:: out | ios:: nocreate);//Clear the node disk.seekp（514+64*index+2*(index/8）); disk<<setw（64）<<''; disk.close(); for(inti=80-superblock.fiptr; I<80; i++)//The node number is found and inserted into the idle node number stack { If (superblock. fistack<index) { superblock.fistack[i-1]=superblock.fistack; } Else//Put in front of the first node number larger than it { superblock.fistack[i-1]=index; break; } } superblock.fiptr++; } //---------------------- /*Group linking method*/ Intballoc()//Requesting a disk block returns the disk block number, otherwise - 1 is returned { inttemp=superblock.fbstack[10-superblock.fbptr]; If (superblock. fbptr==1)//It is at the bottom of the stack==>; It's the recording disk { //Is the last record disk block number 0 (reserved as the bottom of stack allocation failed) if(temp==0) { return-1; } suprblock.fbstack[10-superblock.fbptr]=-1; superblock.fbptr=0; //Reading disk contents into stack for(inti=0; i<10;i++) { intid,num=0; disk.open("disk.txt", ios::in|ios::out|ios::nocreate); //First calculate the number of disks (up to 10), and then the number of disks may be less than 10 disk.seekg（514*temp); for(inti=0; i<10;i++) { disk>>id; num++; if(id==0)break; } disk.seekg（514*temp);// Reading disk contents into stack for(intj=10-num; j<10;j++) { disk>>id; superblock.fbstack[j]=id; } superblock.fbptr=num; disk.close(); } Disk. open ("disk. txt", ios:: in | ios:: out | ios:: nocreate);//Empty the recycle disk disk.seekp（514*temp); disk<<setw（512）<<''; disk.close(); //Disk is used returntemp; } Else//Not a record disk==>; Disk is used { superblock.fbstack[10-superblock.fbptr]=-1; superblock.fbptr--; returntemp; } } //----------------------

FAT

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Under Win 9X, FAT16 The maximum supported partition is 2GB. We know that computers store information in an area called a cluster on the hard disk. The smaller the cluster used, the higher the efficiency of saving information. In the case of FAT16, the larger the partition, the larger the cluster, and the lower the storage efficiency, which will inevitably result in a waste of storage space. And with computer hardware With the continuous improvement of applications, FAT16 file system can no longer meet the requirements of the system. In this case, an enhanced file system was introduced FAT32 。 Compared with FAT16, FAT32 has the following characteristics:
  1. one
    The biggest advantage of FAT32 over FAT16 is that it can support 32GB disks, but cannot support partitions smaller than 512MB.
Windows 2000 based on FAT32 can support partitions up to 32GB; The maximum partition supported by Win 2000 based on FAT16 is 4GB.
  1. one
    With smaller clusters, the FAT32 file system can store information more efficiently. For example, the size of both partitions is 2GB. One partition uses the FAT16 file system, and the other partition uses the FAT32 file system. The cluster size of FAT16 partition is 32KB, while that of FAT32 partition is only 4KB. In this way, the storage efficiency of FAT32 is much higher than that of FAT16, which can generally increase by 15%.
  2. two
    The FAT32 file system can relocate the root directory and use the backup copy of FAT. In addition, the FAT32 partition Startup record It is contained in a structure containing key data, reducing the number of computers [4] System crash Possibility.

NTFS

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ntfs file system It is a file system based on security, which is unique to Windows NT File system structure It is an advanced file system based on the protection of file and directory data, while taking care of saving storage resources and reducing disk usage. Very widely used Windows NT 4.0 The NTFS 4.0 file system is used. I believe that its powerful System security It must have left a deep impression on users. Win 2000 adopts a newer version of NTFS file system NTFS 5.0. Its introduction enables users to not only operate and manage computers as conveniently and quickly as Win 9X, but also enjoy the system security brought by NTFS.
The features of NTFS 5.0 are mainly reflected in the following aspects:
  1. one
    MBR partitions supported by NTFS (if used Dynamic disk It is called volume), which can reach 2TB at most, and GPT partition is unlimited. The FAT32 in Win 2000 supports a maximum size of 2GB for a single file.
  2. two
    NTFS is a recoverable file system. stay NTFS partition Users on rarely need to run a disk repair. NTFS ensures the consistency of partitions by using standard transaction log and recovery technology. NTFS uses log files and checkpoint information when a system failure event occurs Automatic recovery Consistency of the file system.
  3. three
    NTFS supports compression of partitions, folders, and files. Any Windows based application Compressed file Reading and writing do not need to be performed by other programs in advance decompression , when the file is read, the file will be decompressed automatically; Files are automatically compressed when they are closed or saved.
  4. four
    NTFS uses smaller clusters to manage disk space more efficiently. In the case of the FAT32 file system of Win 2000, the cluster size is 4KB when the partition size is between 2GB and 8GB; When the partition size is between 8GB and 16GB, the cluster size is 8KB; When the partition size is between 16GB and 32GB, the cluster size reaches 16KB. In the NTFS file system of Win 2000, when the partition size is less than 2GB, the cluster size is smaller than the corresponding FAT32 cluster; When the partition size is more than 2GB (2GB~2TB), the cluster size is 4KB. In contrast, NTFS can manage disk space more effectively than FAT32, avoiding the waste of disk space to the greatest extent.
  5. five
    On NTFS partitions, you can set access permissions for shared resources, folders, and files. The setting of permission includes two aspects: first, which groups or users are allowed to access folders, files and shared resources; The second is what level of access a group or user can have. The setting of access permission is not only applicable to the users of the local computer, but also to the users passing through the network Shared Folders The network user who accesses the file. Compared with accessing folders or files under FAT32 file system, the security is much higher. In addition, in Win 2000 with NTFS format, apply Audit policy It is possible to Active Directory The object is audited, and the audit results are recorded in security log Through the security log, you can view which groups or users have performed what level of operations on folders, files, or active directory objects, so as to find illegal access that the system may face. By taking appropriate measures, you can minimize this security risk. These cannot be realized under the FAT32 file system.
  6. six
    It can be performed under the NTFS file system of Win 2000 Disk Quota Administration. Disk quota means that administrators can limit the disk space that users can use. Each user can only use the disk space within the maximum quota. After setting the disk quota, you can track and control the disk usage of each user. Through monitoring, you can identify users who have exceeded the quota alarm threshold and quota limit, and then take corresponding measures. The disk quota management function enables administrators to easily and reasonably allocate storage resources to users to avoid possible problems caused by out of control disk space use System crash , which improves the security of the system.
  7. seven
    NTFS uses a Change log to track Record file Changes occurred.

CDFS

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CDFS It is the file system of most discs, and only a small number of discs use other file systems. These file systems can only be used in CD-R or CD-RW Read on.

exFAT

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Extended File Allocation Table Main Interface
(Full name: Extended File Allocation Table File System, extended FAT, that is, extended FAT Document Allocation Table ）Is Microsoft's Windows Embedded 5.0 or higher (including Windows CE 5.0 , 6.0, Windows Mobile 5, 6, 6.1) FAT32 It is launched when 4G and larger files are not supported. For flash memory, ntfs file system Not suitable for use, exFAT More applicable. relative fat file system ExFAT has the following advantages:
1. Enhanced Desktop computer And Mobile Devices Interoperability
2. The maximum size of a single file can reach 16EB (that is, the theoretical value, 16 × 1024 × 1024TB, 1TB=1024G)
3. Cluster size can be up to 32MB
4. Use of spare space Allocation table , Remaining Space allocation Performance improvements
5. The maximum number of files in the same directory can reach 65 536
6. Support access control
7. Support TFAT
Using this file system flash disk I won't support it Windows Vista ReadyBoost。 Windows Vista SP1 The file system is supported.
Please note that exFAT is only a compromise solution, only for USB drive But born.
When formatting a USB flash disk with more than 4GB, the default value is NTFS partition However, this format is very harmful to the USB flash drive, because the NTFS partition uses a "journaling" file system and needs to record detailed read and write operations, it will definitely be more harmful flash disc Chip, because we need to read and write constantly.
Let's see the comparison of exFAT, NTFS, and FAT partitions:
file system
operating system
Minimum sector
Maximum sector
Largest single file
Maximum formatted capacity
Number of files
FAT32
After Win 95 OSR2
512bytes
64KB
2bytes-4GB
2TB (but NT kernel system is limited to 32GB)
four million one hundred and ninety-four thousand three hundred and four
NTFS
After Win2000
512bytes
64KB
Maximum split capacity
2TB~256TB (affected by MBR)
nothing
exFAT
Win CE 6/Vista SP1/Win 8
512bytes
32768KB
16EB (theoretical value)
16EB (theoretical value) (currently up to 256TB)
At least more than 1000

RAW

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RAW file system is a file system generated by the disk without processing or formatting. Generally speaking, these types of file systems may cause normal file systems to become RAW file systems:
● Not formatted.
● format Cancel operation halfway.
● Hard disk appears Bad track 。
● The hard disk has unpredictable errors.
● Viruses Caused by.
The fastest way to solve the RAW file system is to format it immediately and use anti-virus software overall Anti-Virus 。 Of course, if the file is important, you can consider using a disk Data recovery software First save the data, then format and kill the virus, or find some information about“ Raw file system Restore ".

Ext

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Ext2

Ext is GNU/Linux The standard file system in the system is characterized by excellent file access performance. It has more advantages for small and medium-sized files, which mainly benefits from its cluster cache layer Good design 。
Its single file size It is related to the maximum capacity of the file system itself and the cluster size of the file system itself x86 computer system The maximum cluster size is 4KB, the maximum size of a single file is 2048GB, and the maximum size of a file system is 16384GB.
However, since the maximum single partition that can be used by Core 2.4 is only 2048GB, the files that can be used actually system capacity Only 2048GB at most.
as for Ext3 File system, which belongs to a log file system ext2 System expansion. It is compatible with ext2 and is converted from ext2 to ext3 Not complicated.

Ext3

Ext3 Is a kind of Journaled file system , is an extension of ext2 system, which is compatible ext2 。 The advantage of journaling file system is that since all file systems have cache layers to operate, if not in use, the file system must be dismounted to write the cache layer data back to the disk. Therefore, whenever the system needs to be shut down, all its file systems must be shut down before it can be shut down.
If the file system is shut down before it is shut down (such as power failure), the data of the file system will be inconsistent after the next reboot, so the file system must be reorganized at this time to repair the inconsistencies and errors. However, this reorganization is quite time-consuming, especially for file systems with large capacity, and it cannot guarantee that all data will not be lost.
To overcome this problem, use the so-called‘ Journaled file system (Journal File System) ’。 The biggest feature of this kind of file system is that it will completely record the writing action of the entire disk on a certain area of the disk, so that it can be traced back when necessary.
Because the data writing operation contains many details, such as changing the file header data, searching the disk writable space, writing data segments one by one, etc. If every detail is interrupted halfway, the file system will be inconsistent, so it needs to be reorganized.
However, in the journaled file system, because every detail is recorded in detail, when a process is interrupted, the system can directly backtrack and reorganize the interrupted part according to these records, without spending time checking other parts, so the work of reorganization is very fast, almost without taking time.

Ext4

The Linux kernel has officially supported new file systems since 2.6.28 Ext4 。 Ext4 is an improved version of Ext3, which modifies some important data structure , not just like Ext3 pair Ext2 In that way, only a logging function is added. Ext4 can provide better performance and reliability, as well as more functions:
  1. one
    Compatible with Ext3. Execute several commands to migrate from Ext3 online to Ext4 Without reformatting the disk or reformatting Installing the system 。 The original Ext3 data structure is still retained, and Ext4 acts on new data. Of course, the entire file system therefore has a larger capacity supported by Ext4.
  2. two
    Larger file systems and larger files. Compared with the maximum 16TB file system and 2TB files currently supported by Ext3, Ext4 Support 1EB (1048576TB, 1EB=1024PB, 1PB=1024TB) file systems and 16TB files respectively.
  3. three
    Unlimited number of subdirectories. Ext3 currently only supports 32000 subdirectories, while Ext4 supports an unlimited number of subdirectories.
  4. four
    Ext3 uses indirect block mapping, which is extremely inefficient when operating large files. For example, for a 100MB file, 25600 files need to be created in Ext3 data block (Each data block is 4KB in size). and Ext4 The concept of extents, which is popular in modern file systems, is introduced. Each extent is a group of consecutive data blocks. The above file is expressed as "the file data is saved in the next 25600 data blocks", which improves efficiency.
  5. five
    Multi block allocation. When writing data to the Ext3 file system, the Ext3 block allocator can only allocate one 4KB block at a time. Writing a 100MB file requires 25600 calls to the block allocator Ext4 The multi block allocator (mballoc) of supports allocating multiple data blocks in one call.
  6. six
    Delay allocation. Ext3 data block The allocation strategy is to allocate as soon as possible, while the strategy of Ext4 and other modern file operating systems is to delay the allocation as far as possible, and do not start to allocate data blocks and write them to disk until the files are written in the cache. This can optimize the allocation of data blocks for the entire file. Combining with the first two features can significantly improve performance.
  7. seven
    Fast fsck. Previously, the first step of fsck was slow because it needed to check all inodes. Now Ext4 A list of unused inodes has been added to the inode table of each group. In the future, the fsck Ext4 file system can skip them and only check the inodes in use.
  8. eight
    Log verification. The log is the most common part, and it is also easy to cause disk hardware failure. Recovering data from the damaged log will cause more data corruption. The log verification function of Ext4 can easily determine whether the log data is damaged, and it combines the two-phase logging mechanism of Ext3 into one phase, which increases security and improves performance.
  9. nine
    No Journaling mode. Logs always have some overhead, Ext4 Allows you to turn off logs so that some users with special needs can take advantage of this to improve performance.
  10. ten
    Online defragmentation. Although delayed allocation, multi block allocation and extents can effectively reduce file system fragmentation, fragmentation is inevitable. Ext4 supports online defragmentation, and will provide e4defrag tools to defragment individual files or the entire file system.
  11. eleven
    Inode related features. Ext4 It supports larger inodes. Compared with the default size of 128 bytes for Ext3, Ext4 aims to accommodate more extended attributes (such as nanoseconds) in the inode time stamp Or inode version). The default inode size is 256 bytes. Ext4 also supports fast extended attributes and inodes reservation.
  12. twelve
    Persistent preallocation. P2P software often creates an empty file with the same size as the downloaded file in advance to ensure that the downloaded file has enough space to store, so as to avoid download failure due to insufficient disk space in the next few hours or days. Ext4 At the file system level, persistent pre allocation is implemented and the corresponding API (posix_fallocate() in libc) is provided, which is more efficient than the application software's own implementation.
  13. thirteen
    Barrier is enabled by default. The disk is equipped with an internal cache to readjust the write operation sequence of batch data and optimize the write performance. Therefore, the file system must write the commit record after the log data is written to the disk. If the commit record is written first and the log may be damaged, it will affect Data integrity 。 Ext4 The barrier is enabled by default. Only when all the data before the barrier is written to the disk can the data after the barrier be written. (This feature can be disabled with the "mount - o barrier=0" command.)

Btrfs

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Btrfs (Usually read as Butter FS ）, is by Oracle Announced and ongoing in 2007 copy-on-write File system. The goal is to replace Linux current ext3 The file system improves ext3 restrictions, especially the size of a single file, the total file system size, or file checking and adding features not currently supported by ext3, such as writable snapshots snapshots of snapshots、 Built in disk array (RAID) support, and subvolumes. Btrfs also claims to focus on "fault tolerance, repair and ease of management".

ZFS

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ZFS Derived from Sun Microsystems by Solaris Operating system development file system. ZFS is a high storage capacity , file system and Volume Management Concept consolidation, new disks Logical structure The lightweight file system of Storage pool management system 。 ZFS is a CDDL Authorized by the terms of the agreement Open Source Project.

HFS

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HFS file system concept

Tiered File System （Hierarchical File System， HFS ）It is a kind of Apple Computer Developed and used in Mac OS File system on. Originally designed for floppy disk And hard disk, and can also be used on read-only media such as CD-ROM See above.

HFS file system development process

HFS first appeared on September 17, 1985 as Mac The new file system on the intosh computer. It replaces the Flat file System Macintosh File System（ MFS ）。 Because the data generated by Macintosh computer is more than other common file systems, such as DOS Used FAT Or the original Unix file system allows more data to be stored. Apple Computer has developed a new and more applicable file system instead of adopting existing specifications. For example, HFS allows the file name to be up to 31 characters long metadata And dual branch (each file's data and resource branch are stored separately) files.
Although HFS, like most other file systems, is considered a proprietary format, it is the only one that provides good versatility for most of the latest operating systems resolvent To access HFS format disks.

framework

Hierarchical file system divides a volume into many 512 byte“ Logical block ”。 These logical blocks are grouped into "allocation blocks", which can contain one or more logical blocks according to the size of the volume. HFS uses 16 bit values for address allocation blocks. The maximum number of allocation blocks is 65536.
The following five structures are required to form an HFS volume:
  1. one
    Logical blocks 0 and 1 of the volume are boot blocks that contain system boot information. For example, the system name and shell (usually Finder) file loaded at startup.
  2. two
    Logical block 2 contains the master directory block (MDB for short).
  3. three
    Logical block 3 is the boot block of volume bitmap, which tracks the use status of allocation blocks.
  4. four
    The Catalog File is a B * - tree containing records of all files and directories stored in the volume.
  5. five
    The Extension Overflow File is a B * - tree that contains the corresponding information of the allocation block of additional extension records after three extensions in the initial total directory file are occupied.

HFS+

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In 1998, Apple Computer Published HFS+ , which improves the effect of HFS on disk space The efficiency of address location is low, and other improvements are added.
Characteristics of HFS+file system compared with HFS file system
1. Use 32bit to record the number of allocated blocks
HFS and HFS+file systems use disk volumes Blocking Allocate to divide a volume into equal sized allocation blocks. The HFS file system uses 16bit to record the number of allocation blocks, and can only describe 216 allocation blocks at most. For the HFS+file system, 32bit is used to record the number of allocation blocks, which can describe 232 allocation blocks at most. about Mac Non empty data on the system must occupy an integer allocation block, that is, even if a data has only one byte, it must occupy one allocation block. The HFS+file system increases the number of allocation blocks per volume, making the unit space of allocation blocks smaller, thereby reducing storage space The purpose of waste.
2. Tree node size increased to 4KB
The size of directory tree node of HFS file system is 512 bytes, because HFS+files System directory tree Inode Additional pointers and node descriptors need to be stored Two keys Value, the size of the directory tree node of the HFS+file system is increased to 4KB.
3. Single file size Get promoted
The maximum single file size of HFS file system is 2 ^ 31bit, while the maximum single file size of HFS+file system can reach 2 ^ 63bit.
4. Support Long file name
The HFS file system supports up to 31 characters for file names, while the HFS+file system uses Unicode Code, up to 255 characters long.

ReiserFS

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ReiserFS， It is a file system format. The author is Hans Reiser and his team Namesys. On July 23, 1997, he published ReiserFS file system on the Internet. Linux kernel ReiserFS is supported from version 2.4.1.
ReiserFS is named after Hans Reiser, the author. This log file system is more developed than ext2 /3 More recently. Technically, the file system based on B * - tree is used, and its feature is that it can efficiently process large files to many small files; In practice, ReiserFS is even more efficient than ext3 About 10 times faster.
ReiserFS was originally Novell The company's SuSE Linux Enterprise adopted the default file system. Until October 12, 2006, it announced that it would adopt ext3 as the default in future versions. Novell denied that this had anything to do with Hans Reiser's alleged wife killing.

JFS

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JFS (JOURNAL FILE SYSTEM), a byte level log file system, draws on Database protection System technology to record changes in files in the form of logs. JFS Pass Record file Structure rather than data itself changes to ensure the Integrity 。 This method can ensure that the data can be maintained at any time Accessibility 。
This file system is mainly used to meet the requirements of the server (from Single processor system To Advanced Multiprocessor And cluster systems) throughput And reliability requirements. JFS file system is developed for transaction oriented high-performance system. stay IBM Of [5] AIX system JFS has been tested for a long time, and the results show that it is reliable, fast and easy to use. In February 2000, IBM announced the migration under an open resource license Linux version JFS file system. JFS is also an enterprise file system installed and used by a large number of users, with Scalability and Robustness 。 Compared with non log file system, its outstanding advantages are Fast restart Ability, JFS can transfer files in seconds or minutes System recovery To the consistent state. Although JFS is mainly designed to meet the high throughput and reliability requirements of servers (from single processor systems to advanced multiprocessor and cluster systems), it can also be used for servers that want high performance and reliability Client Configuration, because in the System crash JFS can provide fast file system restart time, so it is the Internet File server Of key technology 。 Using database log processing technology, JFS can restore the file system to a consistent state in seconds or minutes. In non journaled file systems, file recovery can take hours or days.
The disadvantage of JFS is that using JFS log file system performance There will be some losses, system resource The occupancy rate is also high, because when it saves a log, the system needs to write a lot of data.

VMFS

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VMware Virtual Machine File System (VMFS) is a high-performance cluster file system that enables [6] Virtualization technology The application of exceeds the limit of a single system. VMFS is designed, built and optimized for [7] Virtual Server Environment, allowing multiple [8] virtual machine Common access to a consolidated cluster Storage pool , thereby significantly improving resources Utilization 。 VMFS is the foundation for virtualization across multiple servers, enabling VMware VmotionTM, Distributed Resource Scheduler, and VMware High Availability And other services. VMFS can also significantly reduce management overhead, providing an efficient virtualization management layer , especially suitable for large enterprises Data Center 。 It can be realized by using VMFS resource sharing , allowing administrators to easily benefit directly from greater efficiency and storage utilization.

XFS

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XFS Yes Silicon Graphics , Inc. developed the file system in the early 1990s. It still serves as SGI be based on IRIX Products from workstation reach [9] Supercomputer ）The underlying file system. Now XFS can also be used for Linux. The arrival of the Linux version of XFS is exciting. First, it provides a robust, excellent and feature rich file system for the Linux community, and the scalability of this file system can meet the most demanding storage requirements.

UFS

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UFS File systems: based on BSD Tradition of high-speed file systems UNIX file system , Yes Solaris The default file system for. UFS logging is enabled by default. In earlier versions of Solaris, the UFS logging feature can only be enabled manually. Solaris 10 is running 64 bit Solaris kernel Multi TB UFS file systems are supported on. Previously, the size of UFS file systems on 64 bit and 32-bit systems was limited to about 1 TB (Tbyte). All UFS file system commands and Utilities Updated to support multi TB UFS file systems.
The UFS1 file system is the default file system for OpenBSD and Solaris. UFS1 also used to be NetBSD and FreeBSD The default file system for NetBSD2.0 and FreeBSD5.0 is UFS2. UFS2 adds support for large files and large capacity disks and some advanced features. At present, it seems that only FreeBSD and NetBSD support UFS2. Apple OS X and Linux UFS1 is also supported, but it is not their default file system.

VXFS

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Veritas FileSystem (VxFS) is the first commercial logging file system. Through the logging function, metadata Changes are first written to the log and then to disk. Since changes do not need to be written in multiple places and metadata is written asynchronously, the throughput is fast. VxFS is also an extensible zone based intention logging file system. VxFS is designed to require high performance and High availability And can handle a large amount of data.

ReFS

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ReFS Resilient File System Windows 8.1 And Server ® A new file system introduced in 2012. ReFS is mostly compatible with NTFS. Its main purpose is to maintain high stability, automatically verify whether the data is damaged, and try to recover the data.
The key functions of ReFS are as follows:
·With checksum metadata Integrity
·Provide optional users Data integrity Integrity flow for.
·Reliable disk updates (also known as Copy on Write ）
·Supports very large volumes, files, and directories
·Storage pooling and virtualization enable file systems to be established and easily managed
·Through data Striping Improve performance (bandwidth can be managed) and improve through backup Fault tolerance
·Prevent potential disk errors through disk scanning
·Restore corruption with "data salvage" to maximize the volume's usability
·Cross computer Shared Storage Pool to provide additional fault tolerance and load balance

WBFS

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WBFS The full name of the file system is Wii Backup File System， Yes Nintendo Household computer wii Game backup mode generated in the research of running backup games. from hacker Invention, in windows It cannot be identified under the system and is used early linux System operation. Mainly for improvement USB storage device Of operating efficiency 。

PFS

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Full name of PFS Playstation File System， As the name suggests Sony For Household computer PS2 For the file system developed by the dedicated hard disk, only PFS Explorer and Winhiip can read it on the computer, and other information is unknown.
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