Ext2 and Ext3 file systems

Article Title: Ext2 and Ext3 file systems. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.
Ext2: it is a standard file system in GNU/Linux systems. It features excellent file access performance and is more advantageous for Small and Medium files, this mainly relies on the excellent design of its cluster cache layer. The size of a single file is related to the upper limit of the file system capacity and the cluster size of the file system. In common x86 computer systems, the maximum size of a cluster is 4 kb, the maximum size of a single file is 2048 GB, and the maximum size of the file system is 16384 GB. However, because the current core 2.4 can only use a single partition of up to 2048 GB, the actual file system capacity is only 2048 GB.
　　
Ext3: as the name suggests, it is the next generation of ext2, that is, adding the log function under the current ext2 format. At present, it is still a step away from the practical stage. Maybe the core of the next version will be ready. Ext3 is a log file system. The advantage of a log file system is that the file system has a cache layer for operation. If the file system is not used, you must detach the file system so that the data on the cache layer can be written back to the disk. Therefore, when the system is shut down, all its file systems must be detached before shutdown.
　　
If the file system is shut down before it is detached (such as power failure), the file system information may be inconsistent after the next reboot. Therefore, the file system must be reorganized, fix inconsistencies and errors. However, this entire task is quite time-consuming, especially for large-capacity file systems, and it cannot guarantee that all data will not be lost. This may cause problems on large servers.
　　
To overcome this problem, the industry has developed for a long time and completed the so-called 'journal File System )'. The most important feature of such a file system is that it records the write operations of the entire disk in a certain area of the disk, so that you can trace back when necessary. Because Data Writing involves many details, such as changing file headers, searching for disk writable space, and writing data segments one by one. If every detail is interrupted, this will cause inconsistency of the file system, and thus need to be reorganized. However, in a log file system, because every detail is recorded in detail, when a process is interrupted, the system can directly refresh and refresh the interrupted part based on these records, it does not have to take time to check other parts. Therefore, the reorganization process is fast and almost no time is required.
　　
In addition, Linux also has a swap file system dedicated to swap partitions. Linux uses the entire partition as the swap space, not Windows uses swap files. Generally, the SWAP partition in this SWAP format is twice the primary memory.