EXT2 and Ext3 file system _unix Linux

EXT2: is the standard file system in the Gnu/linux system, characterized by excellent access to file performance, for small and medium-sized documents more show the advantages, which mainly benefit from its cluster of good design. Its single file size and file system itself is the upper limit of the file system itself and the size of the filesystem itself, in the common x86 computer system, the maximum number of clusters of 4KB, the single file size of the upper limit of 2048GB, and file system capacity of 16384GB. However, because the core 2.4 can use a single partition maximum of only 2048GB, so the actual use of the file system capacity is only 2048GB.

EXT3: As the name suggests, it is the next generation of ext2, in the form of keeping the current ext2, plus the log function. At present it is still a distance from the practical stage, perhaps the next version of the core can be on the road. Ext3 is a log-file system. The advantage of the log-file system is that because the file system has a cache layer involved, you must remove the file system if you do not use it to write the cache data back to disk. Therefore, every time the system shuts down, all of its file systems must be removed before they can be shut down.

If the file system has not been removed before the shutdown (such as a power outage), the next reboot will result in file system data inconsistency, it is necessary to do the reorganization of the file system, will be inconsistent with the wrong place to repair. However, this re-engineering effort is time-consuming, especially with a large capacity document system, and it is not guaranteed that all information will be lost. This can cause problems on large servers.

To overcome this problem, the industry has been developing for a long time, completing the so-called ' log-file system ' (Journal). The biggest feature of this type of file system is that it records the entire disk's write action on one area of the disk so that it can be traced back when needed. Because the data write action contains a lot of details, such as changing the file header data, search disk writable space, write to the data section, and so on, every detail to half if interrupted, it will cause inconsistencies in the file system, and therefore needs to be restructured. However, in the log-file system, as detailed records of each detail, so when interrupted in a certain process, the system can be based on these records directly back and restructure the interrupted part, rather than take the time to check the other parts, so the reorganization of the work speed is very fast, almost no need to spend time.

Additionally Linux has a swap file system dedicated to switching partitions, and Linux uses the entire partition as a swap space, unlike Windows using swap files. The swap partition in this swap format is twice times the main memory.