ReiserFS for local deployment of webgis

Source: Internet
Author: User

ReiserFS File System

1. What is ReiserFS?

ReiserFS is a new type of file system. In blue-point Linux, you can choose it to load your Linux operating system and other applications and data files. It uses a different method-the fully balanced tree structure to accommodate data, including file data, file names, and log support. ReiserFS also supports massive disks and disk arrays, and keeps searching fast and efficient. ReiserFS file systems have been used on high-end Unix systems such as SGI.

2. ReiserFS features (compared with ext2 ):

ReiserFS has many advantages over the traditional file system-ext2 on Linux, which are described in the following sections.

Search Method
ReiserFS is a file system structure based on the Balance Tree, especially for giant file systems with a large number of files, such as file systems on servers, the search speed is faster than ext2; ext2 uses the partial binary search method, the overall performance is inferior to that of ReiserFS.

Space allocation and utilization
The directories in the ReiserFS are completely allocated dynamically, so there is no disk space that ext2 often cannot recycle the giant directories. In the ReiserFS, small files (<4 K) can be directly stored in the tree. The speed of reading and writing small files is faster, and the nodes in the tree are aligned by byte, small files can share the same hard disk block, saving a lot of space. Ext2 uses a fixed block allocation policy. That is to say, small files smaller than 4 K occupy 4 K space, resulting in serious space waste.

Advanced Log Mechanism
ReiserFS has an advanced Journaling/logging mechanism. When the system crashes unexpectedly, incomplete file operations will not affect the integrity of the entire file system structure.
Although ext2 is robust, once the file system is not normally disconnected, it will have to perform a long process of checking the integrity of the system data structure at the next startup, this operation is required to prevent data loss. For larger Server File Systems, this "File System check" may take several hours, which is unacceptable in many cases.
A technology used to solve this problem, "Log File System ". With the help of logs, every change to the data structure is recorded. The log has been written to the hard disk before the actual data is modified. Because of this, when the system suddenly crashes, the system can be restored to a complete system after a few seconds of startup, and the system can be quickly used.

Supports massive disks and excellent overall performance
ReiserFS is a quite modern file system. In contrast, although the performance of ext2 is good, its design is only at the level of 1880s. The emergence of ReiserFS enables Linux to have a high-end, commercial Unix-only advanced file system like Irix/AIX. ReiserFS allows you to easily manage hundreds of GB of file systems. It is useful for enterprise-level applications. Thanks to its efficient storage and fast small file I/O features, it also performs well on the desktop system: the time when the X Window System is started is 1/3 less than that of the ext2 ReiserFS. Ext2 cannot manage a single file larger than 2 GB, which makes ReiserFS superior to ext2 in some large enterprise applications.

3. Disadvantages

One of the most criticized disadvantages of ReiserFS is that the disk will be reformatted every time a version is upgraded, which is also being improved.

4. Origin and future of ReiserFS

In July 23, 1997, Hans Reiser posted his balance tree-based ReiserFS file system on the Internet.
This is the first public appearance of ReiserFS. Since then, ReiserFS has been developing and developing under the development team under Hans Reiser and leadership, SuSE
Linux has also played a major role in its development. Because ReiserFS has some useful features, it is much faster than ext2fs, so it is quickly used by many people. It is said that the Linux kernel version 2.4.0 or later may use ReiserFS as its file system. Currently, ReiserFS can only be used in Intel architecture, but ReiserFS versions supporting other architectures are also under development. We are waiting for a more powerful and more compatible ReiseFS.

All Rights Reserved: cnyun 2006

Ext3 and ReiserFS file systems
Category: Ubuntu, Author: Nicky, Popularity: 16%
This article is a continuation of Ubuntu partition and file system selection, suitable for beginners to understand.

There are many file systems on Linux, such as ext3, ReiserFS, XFS, and JFS. However, ext3 and ReiserFS are commonly used by desktop users. As far as I know, ext3 has a unique advantage in that it is easy to convert between ext2 and ext3, and has good compatibility. Other advantages include ReiserFS, it is also better than it. For example, efficient disk space utilization and unique search methods are not available in ext3, and the speed cannot be comparable to ReiserFS and XFS. In actual use, reiserFS is also more secure and efficient. It is said that the anti-deletion function is also good.

To talk about ext3 and ReiserFS, You can first take a look at the log file system, which is to add the log records of File System Changes to the non-Log File System and track the changes of the file system, and write the changed content into the log. The write operation is first to operate the log file. If the entire write operation is interrupted due to some reason (such as the system power loss), when the system restarts, the write operation before interruption will be restored Based on the log records, and this process takes a very short time. Ext3 and ReiserFS are both log-type file systems with this log function.

Ext3 and reiserfs are RedHat/Suse Linux default file systems, respectively. The advantage of reiserfs is that it is a file system based on the efficient algorithm of B * tree, for example, processing files smaller than 1 K is 10 times faster than ext3. The second is that the reiserfs space is less wasted. It does not allocate inode to some small files, but is packaged and stored in the same disk block (cluster, ext2/ext3 stores them separately on different clusters. If the cluster size is 4 K, two 100-byte files will occupy two clusters, and only one reiserfs will occupy. Of course
Reiserfs also has a disadvantage, that is, the disk must be reformatted every time a version is upgraded.

Because the log file system needs to record logs while writing data, more disk I/O operations are required, it will inevitably lead to performance loss (but ext3 optimizes the movement of the hard disk head, and the total processing capacity is not slower than ext2 ). In addition, when the log file system frequently records logs, it also generates more disk fragments than non-log file systems such as ext2 (although these fragments are nothing compared to FAT32 ). Therefore, we recommend that you use a hybrid File System for some materials. For example, read-only directories/usr use ext2 to use ext3 for directories that frequently write data to/var, however, I think reiserfs is a better choice for desktop users.
Ext3 is faster, with fewer fragments than ext3.

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