(Thus appends and new files have the same level of integrity protection as the "journaled" level.) However, files being overwritten can be corrupted because the original version of the file is not stored. If there is a power outage or kernel panic while a file is being written or appended to, the journal will indicate that the new file or appended data has not been "committed", so it will be purged by the cleanup process. This is the default on many Linux distributions. Ordered (medium risk) Only metadata is journaled file contents are not, but it's guaranteed that file contents are written to disk before associated metadata is marked as committed in the journal. In other cases, performance gets worse, because the data must be written twice-once to the journal, and once to the main part of the filesystem. Because the journal is relatively continuous on disk, this can improve performance, if the journal has enough space. Journal (lowest risk) Both metadata and file contents are written to the journal before being committed to the main file system. There are three levels of journaling available in the Linux implementation of ext3: ^ In Linux, 8 KiB block size is only available on architectures which allow 8 KiB pages, such as Alpha.The size of a block can vary, affecting the maximum number of files and the maximum size of the file system: Block size The maximum number of blocks for ext3 is 2 32. In significant data corruption, ext2 or ext3 may be recoverable, while a tree-based file system may not. The file system metadata is all in fixed, well-known locations, and data structures have some redundancy. This situation might sometimes be a disadvantage, but for recoverability, it is a significant advantage. The close relationship also makes conversion between the two file systems (both forward to ext3 and backward to ext2) straightforward.Įxt3 lacks "modern" filesystem features, such as dynamic inode allocation and extents. The ext2 and ext3 file systems share the same standard set of utilities, e2fsprogs, which includes an fsck tool. This situation has allowed well-tested and mature file system maintenance utilities for maintaining and repairing ext2 file systems to also be used with ext3 without major changes. Without these features, any ext3 file system is also a valid ext2 file system. HTree indexing for larger directories.Įxt3 adds the following features to ext2: It is also considered safer than the other Linux file systems, due to its relative simplicity and wider testing base. Benchmarks suggest that ext3 also uses less CPU power than ReiserFS and XFS. The performance (speed) of ext3 is less attractive than competing Linux filesystems, such as ext4, JFS, ReiserFS, and XFS, but ext3 has a significant advantage in that it allows in-place upgrades from ext2 without having to back up and restore data. 2.7 Near-time extinction due to date-stamp limitation.Its main advantage over ext2 is journaling, which improves reliability and eliminates the need to check the file system after an unclean shutdown. The filesystem was merged with the mainline Linux kernel in November 2001 from 2.4.15 onward. Stephen Tweedie first revealed that he was working on extending ext2 in Journaling the Linux ext2fs Filesystem in a 1998 paper, and later in a February 1999 kernel mailing list posting. It used to be the default file system for many popular Linux distributions. #INCONSISTENT EXTFS ARCHIVE WINDOWS#Linux, BSD, ReactOS, Windows (through an IFS)Įxt3, or third extended filesystem, is a journaled file system that is commonly used by the Linux kernel. Unix permissions, ACLs and arbitrary security attributes (Linux 2.6 and later) Modification (mtime), attribute modification (ctime), access (atime)Īllow-undelete, append-only, h-tree (directory), immutable, journal, no-atime, no-dump, secure-delete, synchronous-write, top (directory) Table, hashed B-tree with dir_index enabled
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