Ext3 file system, REISERFS,XFS,JSF that kind of performance.

Ext2 is an old Linux file system with no log functionality. The time that is enabled usually takes long. At present, there are many log patterns of the file Eucalyptus system can be faster and better efficiency to complete the system to enable and check.

The ext3 is a log version of Ext2, which provides a metadata log system and can be used quickly to restore the log system. Ext3 is a fairly good and reliable system for filing eucalyptus. It has an extra hashed b-tree indexing feature that opens him up after almost any situation is high performance. You can start this function with the MKE2FS command Plus-o dir_index. Simply put, ext3 is a very outstanding system for filing eucalyptus.

ReiserFS is a pretty good system overall, and it's better to handle smaller files (less than 4KB) than Ext2 and ext3. He is using a b*-tree-based system for filing eucalyptus. In addition, the large-scale eucalyptus can be handled efficiently. After the Linux core version 2.4.18+, ReiserFS is a highly recommended system, from very few to many files. ReiserFS can handle it very well. It is not recommended to use this file for the boot partition system.

XFS is a metadata log system with full functionality and scalability optimization. If you use high-speed SCSI or fiber storage and have a continuous power supply, we recommend you use XFS. If not, please use a different file Eucalyptus system. Because XFS has a large amount of data to be forwarded in memory, poorly designed programs (and indeed some programs that do not do general precautions when writing to the disk) may lose large amounts of data when the system unexpectedly loses power.

JFS is an efficient logging system developed by IBM. At present, although it can be regarded as a finished product, about his stability is not too many advantages and disadvantages.

EXT3 is the third-generation extended file System (English: Third extended filesystem, abbreviated as EXT3), is a log file system, commonly used in Linux operating systems. It is the default file system for many Linux distributions. In the February 1999 kernel mailing list, Stephen Tweedie first showed that he was using the extended ext2, which began with the 2.4.15 kernel and merged into the kernel mainline.

If the file system is not shutdown before the shutdown, such as (power outage), the next reboot will result in inconsistent file system data, it is necessary to do the file system reorganization work, will be inconsistent with the wrong place to repair. However, this reorganization of the work is quite time-consuming, especially the large-capacity file system, but also cannot guarantee that all the information will not be lost. To overcome this problem, use the so-called "journaled file System" (Journal). The biggest feature of such a file system is that it records the entire disk's write action on a region of the disk, so that it can be traced back if necessary. Because the data write action contains many details, such as changing the file header data, the search disk can write to the space, write the data section, and so on, every detail toFlight Data Recovery Center providesIf half is interrupted, it causes inconsistencies in the file system and therefore needs to be restructured. However, in the journaled file system, due to the detailed record of each detail, so when in a process is interrupted, the system can directly backtrack and restructure the interrupted parts according to these records, without having to take the time to check the other parts, so the reorganization of the work speed is very fast, almost no need to spend time.2 Advantages While its performance (speed) is not as good as its competitors, such as Jfs2,reiserfs and XFS, it has an important advantage that it allows upgrades from popular ext2 file systems at the right time without the need to back up and recover data; It also has a lower CPU usage than ReiserFS and XFS. The addition of the Ext3 file system beyond its predecessor includes: • Log A bit directory provides a tree-based directory index spanning multiple blocks · Online system growth without these, the Ext3 file system is also a valid ext2 file system. In this way, well-tested, proven file system tools to manage and repair Ext2 file system tools can be applied to the Ext3 file system without major changes. The ext2 and Ext3 file systems share the same toolset, e2fsprogs with the fsck tool. This close connection also makes it very easy to convert between two file systems, including upgrading to ext3 and downgrading to ext2. Linux implements the Ext3 file system, which includes 3 levels of logs:Diary(slow, but less risky) metadata and file content are written before committing to the primary file system. This improves stability but has a performance penalty because all data is written 2 times. If you do not add this option in the/etc/fstab, the modified file in the case of kernel panic or sudden power outage may occur when the damage, of course, it depends on how the software is written to the file.Order(Medium-speed, moderate-risk) sequence and Write backSimilar, but forces the file contents to be written before the corresponding metadata is marked for commit. This is the default way for many Linux distributions.Write back(Fast, but with the greatest risk; in some sense it is equivalent to ext2): There is only metadata to write to the log, and the contents of the file are not written to the log. This makes the whole efficiency much faster, but it also causes the file to be written out of order. For example, if the file is crash at the same time as the additional size, it may cause a heap of junk data to be appended to the file after the next mount. Although Ext3 lacks some of the characteristics of contemporary file systems, such as dynamic inode, tree-like data storage structure and so on, are regarded as one of the shortcomings of ext3, but in addition to these features, ext3 in the file system reply above has a good performance. Compared to the tree-like file system, the ext3 above metadata is placed in a fixed position, and the writing will be repeated at the same time some of the data to be written to EXT2/3 in the face of data corruption and the opportunity to recover.3 Disadvantages functionThe original design goal of EXT3 was to provide a high degree of compatibility with ext2, and many disks were similar in structure to ext2. Because of this, ext3 lacks many of the latest features in the design, such as dynamically allocating inode and variable block size (frags or tails). The ext3 file system cannot be fsck when it is mounted as a write. The dumping of the ext3 file system may cause damage to the data when the file system is still mounted. EXT3 does not support extensions that have been supported on other file systems (for example: JFS2 and EXT4).Disk FragmentationAt the file system level, there is no online ext3 defrag tool. The Offline ext2 defrag tool E2defrag can be used for ext3 file systems, but only if the file system is converted back to ext2 before use. But relying on the function bit to open in the file system, E2defrag may destroy the data, still do not know how to deal with the new ext3 function. There are a number of Disk Defragmenter tools that users use, such as shake and defrag, that are not fragmented by copying files to implement newly allocated files. However, this is only valid if the file system is fairly empty, and the file system does not often fragment. There is currently no real disk defragmentation tool for ext3. In fact, Defrag is an old habit that people get into when they work in single-user single-process environments, such as dos/early windows. In a multitasking environment, the advent of disk fragmentation is fundamentally unavoidable, and fragmentation is fast. The task of the operating system is not to provide users with a clean-up tool, but to eliminate fragmentation damage to performance when the system is designed. For example, the Linux block device operation has to go through an I/O scheduling layer, by using a scheduling strategy with elevator algorithm in the scheduling layer to eliminate the impact of fragmentation on performance. In addition, the concept of disk fragmentation can become a history if future SSDs are popularized or replaced by traditional hard drives.Anti-deleteUnlike Ext2, Ext3 clears the block metrics in the file's node (inode) when the file is deleted. This can reduce access to the file system when the unclean is loaded into the file system and the log is replayed. But it also adds to the difficulty of removing the files above the anti-deletion. The only remedy for the user is to skim the data on the hard drive and to know the block metrics from the beginning to the end of the file. While providing a slightly higher level of security than ext2 in deleting files, there is also an unavoidable inconvenience.CompressionEXT3 does not support transparent compression (EXT2 is supported by unofficial patches).Size LimitThe ext3 has a relatively small maximum size for individual files and for the entire file system. These limits depend on the block size of the file system, and the following table summarizes these limitations:

Block size	Maximum file size	Maximum file system size
1KiB	16GiB	2TiB
2KiB	256GiB	8TiB
4KiB	2TiB	16TiB
8KiB	16TiB	32TiB

8KiB blocks, which can only be used for schemas that allow 8KiB pages (such as Alpha).There is no checksum in the logEXT3 does not do checksums when writing to a log. If Barrier=1 does not act as a load parameter (in file/etc/fstab), and if the hardware is in an out-of-order write cache, it can severely damage the file system when it crashes (this option is not enabled in most popular Linux distributions, so most distributions are in a dangerous situation.) Consider the following scenario: If the hard disk writes out of order (because the hard disk now uses a caching mechanism to amortize the write speed), then it is possible that other related blocks have been written to the commit block of the write processing. If the power is down and the kernel panic appears before the other blocks are written, the system will have to be restarted. After a reboot, the file system repeats the log in the normal manner and repeats the "winner" (with the processing of the commit block, including the above invalid but marked as valid commit block). As a result, the disk writes that are not completed above will be processed, but the log data that has been corrupted is used. When the file system repeats the log, it overwrites the normal data with the bad data. . If a checksum is used (if the fake "winner" handles a checksum that is marked as mutually exclusive), the file system will handle it better and will not replay the wrong data on the disk. [1] As of June 24, 2007, there have been patches to fix the problem.4Ext3 log file system features 1, the high-availability system uses the Ext3 file system, even after the abnormal shutdown, the system does not need to check the file system. When the outage occurs, it takes only 10 seconds to recover the ext3 file system. 2, the integrity of the data Ext3 file system can greatly improve the integrity of the file system, to avoid accidental downtime of the file system damage. The Ext3 file system has 2 modes to choose from to ensure data integrity. One of these is the "Keep file system and data consistent" mode. In this way, you will never see junk files stored on disk because of an unhealthy shutdown. 3. File system speed while using the Ext3 file system, it is sometimes possible to write data multiple times while storing data, but in general, Ext3 is better than ext2 performance. This is because the Ext3 log feature optimizes the drive read-write header for the disk. Therefore, the performance of the file system is not degraded compared to the Ext2 file system. 4, data conversion from the Ext2 file system to the Ext3 file system is very easy, as long as the simple type of two commands to complete the entire conversion process, users do not have to spend time to backup, restore, format partition and so on. With a gadget tune2fs provided by a ext3 file system, it can easily convert ext2 file systems to ext3 log file systems. In addition, the Ext3 file system can be loaded directly into the ext2 file system without any changes. 5, a variety of log mode Ext3 have a variety of log mode, a mode of operation is to all the file data and metadata (define the file system data, that is, data) logging (data=journal mode) Another mode of operation is to log only the metadata, not the data, the so-called data=ordered or Data=writeback mode. The System Manager can choose between the system's working speed and the consistency of the file data according to the actual work requirement of the system. [3]5Ext3 Overview ext3 Index NodeDeveloper: Open Source full name: Third extended file system release date: November 2001 (Linux 2.4.15) partition ID: 0x83 (MBR) ; Ebd0a0a2-b9e5-4433-87c0-68b6b72699c7 (GPT)

Ext3 file system, REISERFS,XFS,JSF that kind of performance.