File System Management, File System

File System Management, File System

1. Overview of file systems

1. A file system is a system software based on an operating system used to manage and organize data stored on a disk drive, by managing data storage layout, space management, file naming, and security control, you can effectively store data on devices.

2. the file system is a bridge between the operating system and the disk device. The file system enables reasonable data organization and effective access, as shown in the management of files and directories in the operating system.

3. metadata: In addition to storing and managing data stored in files, the file system also stores important information about files and the file system itself (such as file permissions/size/owner) stored on a disk. This information is called the metadata of the file system (metadata)

4. Procedure for using the file system:

Syntax: mkfs [-v] [-t fstype] Device

• -V: displays the mkfs version.
• -T fstype: Specifies the file system type created. If this option is not added, the default value is ext2.
• Device: disk or disk partition to be formatted

Example: mkfs-t ext3

4. mount a device: the process of associating a file system with a storage is called mounting.

Ii. ext3 and ext4 file systems

1. Introduction: The most common file systems in linux: ext2/ext3/ext4/ReiserFS/XFS. The linux standard file starts with VFS and then ext -- ext2 -- ext3.

2. ext2 is a standard file system on linux.

3. ext3 File System

It is a log file system. In fact, it adds a special incode (log file), that is, the logging function, to the ext2 file system. Based on different Log File System implementation technologies, ext3 provides three log modes:

• Journal mode: all data and metadata changes in the file system are written into logs. The safest and slowest.
• Ordered mode: logs are recorded only when metadata of the file system is modified. Default mode.
• Writeback mode: Metadata is updated before data is updated. The fastest.

4. ext4 file system features:

• More subdirectories supported: theoretically, an unlimited number is supported.
• Support for larger file systems and larger files: The file system capacity reaches 1 EB, and the file capacity reaches 16 TB.
• Supported disk structure
• Log verification is supported.
• Fast fsck supported
• Support online Fragment

5. ReiserFs

Manages data in a fully balanced structure, including file data/file name and log support. The features are as follows:

• Efficient and rational use of disk space
• Advanced Log Management Mechanism
• Unique search method: Fast balancing tree-based search method
• Support for massive disk storage

If the application system has many small files and a large number of read/write operations, the ReiserFS file system is definitely the first choice.

6. XFS

(1) features:

• Excellent logging functions
• High scalability
• Fast Write Performance

(2) Use

• File System formatting command: mkfs. xfs
• File System fragment command: xfs_fsr
  • Xfs_bmap: view the file block status
  • Xfs_db: view disk shards
  • Xfs_fsr: Fragment
• File System consistency Detection: xfs_repair

3. File System Selection Criteria