From owner-svn-doc-projects@FreeBSD.ORG Mon Jul 29 22:28:21 2013 Return-Path: Delivered-To: svn-doc-projects@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id B4FD0A6B; Mon, 29 Jul 2013 22:28:21 +0000 (UTC) (envelope-from wblock@FreeBSD.org) Received: from svn.freebsd.org (svn.freebsd.org [IPv6:2001:1900:2254:2068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id A1042245C; Mon, 29 Jul 2013 22:28:21 +0000 (UTC) Received: from svn.freebsd.org ([127.0.1.70]) by svn.freebsd.org (8.14.7/8.14.7) with ESMTP id r6TMSLLu059177; Mon, 29 Jul 2013 22:28:21 GMT (envelope-from wblock@svn.freebsd.org) Received: (from wblock@localhost) by svn.freebsd.org (8.14.7/8.14.5/Submit) id r6TMSLA6059176; Mon, 29 Jul 2013 22:28:21 GMT (envelope-from wblock@svn.freebsd.org) Message-Id: <201307292228.r6TMSLA6059176@svn.freebsd.org> From: Warren Block Date: Mon, 29 Jul 2013 22:28:21 +0000 (UTC) To: doc-committers@freebsd.org, svn-doc-projects@freebsd.org Subject: svn commit: r42473 - projects/zfsupdate-201307/en_US.ISO8859-1/books/handbook/filesystems X-SVN-Group: doc-projects MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-doc-projects@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: SVN commit messages for doc projects trees List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 29 Jul 2013 22:28:21 -0000 Author: wblock Date: Mon Jul 29 22:28:20 2013 New Revision: 42473 URL: http://svnweb.freebsd.org/changeset/doc/42473 Log: Update the ZFS section with Allan Jude's latest diff. Modified: projects/zfsupdate-201307/en_US.ISO8859-1/books/handbook/filesystems/chapter.xml Modified: projects/zfsupdate-201307/en_US.ISO8859-1/books/handbook/filesystems/chapter.xml ============================================================================== --- projects/zfsupdate-201307/en_US.ISO8859-1/books/handbook/filesystems/chapter.xml Mon Jul 29 21:34:24 2013 (r42472) +++ projects/zfsupdate-201307/en_US.ISO8859-1/books/handbook/filesystems/chapter.xml Mon Jul 29 22:28:20 2013 (r42473) @@ -139,8 +139,8 @@ - zpool + zpool A storage pool is the most basic building block of ZFS. A pool is made up of one or more vdevs, the @@ -161,8 +161,8 @@ - vdev Types + vdev Types A zpool is made up of one or more vdevs, which themselves can be a single disk or a group of disks, @@ -171,8 +171,7 @@ increase performance and maximize usable space. - + Disk - The most basic type of vdev is a standard block device. This can be an entire disk (such as @@ -187,8 +186,7 @@ - + File - In addition to disks, ZFS pools can be backed by regular files, this is especially useful for testing and @@ -199,8 +197,7 @@ - + Mirror - When creating a mirror, specify the mirror keyword followed by the list of member devices @@ -222,8 +219,7 @@ - + RAID-Z - ZFS implements RAID-Z, a variation on standard RAID-5 that offers better distribution of parity @@ -267,8 +263,7 @@ - + Spare - ZFS has a special pseudo-vdev type for keeping track of available hot spares. Note that installed hot spares are @@ -278,8 +273,7 @@ - + Log - ZFS Log Devices, also known as ZFS Intent Log (ZIL) move the intent log from the regular pool @@ -300,8 +294,7 @@ - + Cache - Adding a cache vdev to a zpool will add the storage of the cache to the L2ARC. Cache devices cannot be mirrored. @@ -313,8 +306,8 @@ - Adaptive Replacement + Adaptive Replacement Cache (ARC) ZFS uses an Adaptive Replacement Cache @@ -346,8 +339,8 @@ - L2ARC + L2ARC The L2ARC is the second level of the ZFS caching system. The @@ -385,8 +378,8 @@ - Copy-On-Write + Copy-On-Write Unlike a traditional file system, when data is overwritten on ZFS the new data is written to a @@ -402,26 +395,44 @@ - Dataset + Dataset - + Dataset is the generic term for a ZFS file + system, volume, snapshot or clone. Each dataset will + have a unique name in the format: + poolname/path@snapshot. The root + of the pool is technically a dataset as well. Child + datasets are named hierarchically like directories; + for example mypool/home, the home + dataset is a child of mypool and inherits properties + from it. This can be expended further by creating + mypool/home/user. This grandchild + dataset will inherity properties from the parent and + grandparent. It is also possible to set properties + on a child to override the defaults inherited from the + parents and grandparents. ZFS also allows + administration of datasets and their children to be + delegated. - Volume + Volume - In additional to regular file systems (datasets), + In additional to regular file system datasets, ZFS can also create volumes, which are block devices. Volumes have many of the same features, including copy-on-write, snapshots, clones and - checksumming. + checksumming. Volumes can be useful for running other + file system formats on top of ZFS, such as UFS or in + the case of Virtualization or exporting + iSCSI extents. - Snapshot + Snapshot The copy-on-write @@ -464,8 +475,8 @@ - Clone + Clone Snapshots can also be cloned; a clone is a writable version of a snapshot, allowing the file @@ -487,8 +498,8 @@ - Checksum + Checksum Every block that is allocated is also checksummed (which algorithm is used is a per dataset property, @@ -513,8 +524,8 @@ - Compression + Compression Each dataset in ZFS has a compression property, which defaults to off. This property can be set to @@ -531,8 +542,8 @@ - Deduplication + Deduplication ZFS has the ability to detect duplicate blocks of data as they are written (thanks to the checksumming @@ -573,8 +584,8 @@ - Scrub + Scrub In place of a consistency check like fsck, ZFS has the scrub command, which reads @@ -592,9 +603,8 @@ - Dataset - Quota + Dataset Quota ZFS provides very fast and accurate dataset, user and group space accounting in addition to quotes and @@ -624,8 +634,8 @@ - Reference + Reference Quota A reference quota limits the amount of space a @@ -637,27 +647,27 @@ - User - Quota + User + Quota User quotas are useful to limit the amount of space that can be used by the specified user. - - Group - Quota + Group + Quota The group quota limits the amount of space that a specified group can consume. - Dataset - Reservation + Dataset + Reservation The reservation property makes it possible to guaranteed a minimum amount of space @@ -683,9 +693,9 @@ - Reference - Reservation + Reference + Reservation The refreservation property makes it possible to guaranteed a minimum amount of @@ -710,10 +720,15 @@ - Resilver + Resilver - + When a disk fails and must be replaced, the new + disk must be filled with the data that was lost. This + process of calculating and writing the missing data + (using the parity information distributed across the + remaining drives) to the new drive is called + Resilvering. @@ -724,7 +739,33 @@ What Makes ZFS Different - + ZFS is significantly different from any previous file + system owing to the fact that it is more than just a file + system. ZFS combines the traditionally separate roles of + volume manager and file system, which provides unique + advantages because the file system is now aware of the + underlying structure of the disks. Traditional file systems + could only be created on a single disk at a time, if there + were two disks then two separate file systems would have to + be created. In a traditional hardware RAID + configuration, this problem was worked around by presenting + the operating system with a single logical disk made up of + the space provided by a number of disks, on top of which the + operating system placed its file system. Even in the case of + software RAID solutions like GEOM, the UFS + file system living on top of the RAID + transform believed that it was dealing with a single device. + ZFS's combination of the volume manager and the file system + solves this and allows the creation of many file systems all + sharing a pool of available storage. One of the biggest + advantages to ZFS's awareness of the physical layout of the + disks is that ZFS can grow the existing file systems + automatically when additional disks are added to the pool. + This new space is then made available to all of the file + systems. ZFS also has a number of different properties that + can be applied to each file system, creating many advantages + to creating a number of different filesystems and datasets + rather than a single monolithic filesystem.