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Reiser4 is a computer file system, successor to the ReiserFS file system, developed from scratch by Namesys and sponsored by DARPA as well as Linspire. Reiser4 was named after its former lead developer Hans Reiser. As of 2015, the Reiser4 patch set is still being maintained, but according to Phoronix, it's unlikely to be merged into mainline Linux without corporate backing.〔 == Features == Some of the goals of the Reiser4 file system are: * Different transaction models: Journaling, Write-Anywhere (Copy-on-Write), Hybrid transaction model〔(【引用サイトリンク】title=Reiser4 transaction models )〕 * More efficient journaling through wandering logs * More efficient support of small files, in terms of disk space and speed through block suballocation * Liquid items (or virtual keys) - a special format of records in the storage tree, which completely resolves the problem of internal fragmentation * EOTTL (extents on the twig level) - fully balanced storage tree, meaning that all paths to objects are of equal length * Faster handling of directories with large numbers of files * Transparent compression (LZO, ZLIB) * Plugin infrastructure * Dynamically optimized disk-layout through allocate-on-flush (also called delayed allocation in XFS) * Delayed actions (tree balancing, compression, block allocation, local defragmentation) * R and D (Rare and Dense) caches, synchronized at commit time * Transactions support for user-defined integrity * Data checksums (currently only for files managed by cryptcompress plugin) * Precise discard support〔(【引用サイトリンク】title=PreciseDiscard )〕 with delayed issuing of discard requests for SSD devices〔(【引用サイトリンク】title=Reiser4 discard support )〕 Some of the more advanced Reiser4 features (such as user-defined transactions) are also not available because of a lack of a VFS API for them. At present Reiser4 lacks a few standard file system features, such as an online repacker (similar to the defragmentation utilities provided with other file systems). The creators of Reiser4 say they will implement these later, or sooner if someone pays them to do so. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Reiser4」の詳細全文を読む スポンサード リンク
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