Difference between revisions of "File systems"

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[[Category:File systems]]
 
[[Category:File systems]]
[[es:File Systems]]
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[[es:File systems]]
[[It:File Systems]]
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[[hu:File systems]]
[[ja:File Systems]]
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[[it:File systems]]
[[pl:File Systems]]
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[[ja:ファイルシステム]]
[[zh-cn:File Systems]]
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[[pl:File systems]]
{{Article summary start}}
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[[zh-cn:File systems]]
{{Article summary text|An overview of the types of file systems available.}}
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{{Related articles start}}
{{Article summary heading|Related}}
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{{Related|Core utilities#lsblk}}
{{Article summary wiki|Partitioning}}
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{{Related|File permissions and attributes}}
{{Article summary end}}
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{{Related|fsck}}
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{{Related|fstab}}
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{{Related|List of applications/Internet#Distributed file systems}}
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{{Related|List of applications#Mount tools}}
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{{Related|Optical disc drive}}
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{{Related|Partitioning}}
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{{Related|NFS}}
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{{Related|NTFS-3G}}
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{{Related|FAT}}
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{{Related|QEMU#Mounting a partition inside a raw disk image}}
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{{Related|Samba}}
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{{Related|tmpfs}}
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{{Related|udev}}
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{{Related|udisks}}
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{{Related|umask}}
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{{Related|USB storage devices}}
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 +
{{Related articles end}}
  
 
From [[Wikipedia:File system|Wikipedia]]:
 
From [[Wikipedia:File system|Wikipedia]]:
:''A file system (or filesystem) is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device(s) which contain it. A file system organizes data in an efficient manner and is tuned to the specific characteristics of the device.''
+
:In computing, a file system (or filesystem) is used to control how data is stored and retrieved. Without a file system, information placed in a storage medium would be one large body of data with no way to tell where one piece of information stops and the next begins. By separating the data into pieces and giving each piece a name, the information is easily isolated and identified.
 +
:Taking its name from the way paper-based information systems are named, each group of data is called a "file". The structure and logic rules used to manage the groups of information and their names is called a "file system".
 +
 
 +
Individual drive partitions can be setup using one of the many different available filesystems. Each has its own advantages, disadvantages, and unique idiosyncrasies. A brief overview of supported filesystems follows; the links are to Wikipedia pages that provide much more information.
 +
 
 +
== Types of file systems ==
 +
 
 +
See {{man|5|filesystems}} for a general overview, and [[Wikipedia:Comparison of file systems]] for a detailed feature comparison. File systems supported by the kernel are listed in {{ic|/proc/filesystems}}.
 +
 
 +
{| class="wikitable sortable"
 +
! File system
 +
! Creation command
 +
! Userspace utilities
 +
! [[Archiso]] [https://git.archlinux.org/archiso.git/tree/configs/releng/packages.both]
 +
! Kernel documentation [https://www.kernel.org/doc/Documentation/filesystems/]
 +
! Notes
 +
|-
 +
| [[Btrfs]]
 +
| {{man|8|mkfs.btrfs}}
 +
| {{Pkg|btrfs-progs}}
 +
| {{Yes}}
 +
| [https://www.kernel.org/doc/Documentation/filesystems/btrfs.txt btrfs.txt]
 +
| [https://btrfs.wiki.kernel.org/index.php/Status Stability status]
 +
|-
 +
| [[VFAT]]
 +
| {{man|8|mkfs.vfat|url=}}
 +
| {{Pkg|dosfstools}}
 +
| {{Yes}}
 +
| [https://www.kernel.org/doc/Documentation/filesystems/vfat.txt vfat.txt]
 +
|
 +
|-
 +
| [[w:exFAT|exFAT]]
 +
| {{man|8|mkfs.exfat|url=}}
 +
| {{Pkg|exfat-utils}}
 +
| {{Y|Optional}}
 +
| N/A (FUSE-based)
 +
|
 +
|-
 +
| [[F2FS]]
 +
| {{man|8|mkfs.f2fs|url=}}
 +
| {{Pkg|f2fs-tools}}
 +
| {{Yes}}
 +
| [https://www.kernel.org/doc/Documentation/filesystems/f2fs.txt f2fs.txt]
 +
 
 +
| Flash-based devices
 +
|-
 +
| [[ext3]]
 +
| {{man|8|mke2fs}}
 +
| {{Pkg|e2fsprogs}}
 +
| {{Yes}} ({{Grp|base}})
 +
| [https://www.kernel.org/doc/Documentation/filesystems/ext3.txt ext3.txt]
 +
|
 +
|-
 +
| [[ext4]]
 +
| {{man|8|mke2fs}}
 +
| {{Pkg|e2fsprogs}}
 +
| {{Yes}} ({{Grp|base}})
 +
| [https://www.kernel.org/doc/Documentation/filesystems/ext4.txt ext4.txt]
 +
|
 +
|-
 +
| [[w:Hierarchical_File_System|HFS]]
 +
| {{man|8|mkfs.hfsplus|url=}}
 +
| {{Pkg|hfsprogs}}
 +
| {{Y|Optional}}
 +
| [https://www.kernel.org/doc/Documentation/filesystems/hfs.txt hfs.txt]
 +
| [[w:macOS|macOS]] file system
 +
|-
 +
| [[JFS]]
 +
| {{man|8|mkfs.jfs|url=}}
 +
| {{Pkg|jfsutils}}
 +
| {{Yes}} ({{Grp|base}})
 +
| [https://www.kernel.org/doc/Documentation/filesystems/jfs.txt jfs.txt]
 +
|
 +
|-
 +
| [[Wikipedia:NILFS|NILFS2]]
 +
| {{man|8|mkfs.nilfs2|url=}}
 +
| {{Pkg|nilfs-utils}}
 +
| {{Yes}}
 +
| [https://www.kernel.org/doc/Documentation/filesystems/nilfs2.txt nilfs2.txt]
 +
|
 +
|-
 +
| [[NTFS]]
 +
| {{man|8|mkfs.ntfs|url=}}
 +
| {{Pkg|ntfs-3g}}
 +
| {{Yes}}
 +
| N/A (FUSE-based)
 +
| [[w:Microsoft_Windows|Windows]] file system
 +
|-
 +
| [[Reiser4]]
 +
| {{man|8|mkfs.reiser4|url=}}
 +
| {{AUR|reiser4progs}}
 +
| {{No}}
 +
|
 +
|
 +
|-
 +
| [[w:ReiserFS|ReiserFS]]
 +
| {{man|8|mkfs.reiserfs|url=}}
 +
| {{Pkg|reiserfsprogs}}
 +
| {{Yes}} ({{Grp|base}})
 +
|
 +
|
 +
|-
 +
| [[XFS]]
 +
| {{man|8|mkfs.xfs}}
 +
| {{Pkg|xfsprogs}}
 +
| {{Yes}} ({{Grp|base}})
 +
|
 +
[https://www.kernel.org/doc/Documentation/filesystems/xfs.txt xfs.txt]<br>
 +
[https://www.kernel.org/doc/Documentation/filesystems/xfs-delayed-logging-design.txt xfs-delayed-logging-design.txt]<br>
 +
[https://www.kernel.org/doc/Documentation/filesystems/xfs-self-describing-metadata.txt xfs-self-describing-metadata.txt]
 +
|
 +
|-
 +
| [[ZFS]]
 +
|
 +
| {{AUR|zfs-linux}}
 +
| {{No}}
 +
| N/A ([[w:OpenZFS|OpenZFS]] port)
 +
|
 +
|}
 +
 
 +
{{Note|The kernel has its own NTFS driver (see [https://www.kernel.org/doc/Documentation/filesystems/ntfs.txt ntfs.txt]), but it has limited support for writing files.}}
 +
 
 +
=== Journaling ===
 +
 
 +
All the above filesystems with the exception of ext2, FAT16/32, use [[Wikipedia:Journaling_file_system|journaling]]. Journaling provides fault-resilience by logging changes before they are committed to the filesystem. In the event of a system crash or power failure, such file systems are faster to bring back online and less likely to become corrupted. The logging takes place in a dedicated area of the filesystem.
 +
 
 +
Not all journaling techniques are the same. Ext3 and ext4 offer data-mode journaling, which logs both data and meta-data, as well as possibility to journal only meta-data changes. Data-mode journaling comes with a speed penalty and is not enabled by default. In the same vein, [[Reiser4]] offers so-called [https://reiser4.wiki.kernel.org/index.php/Reiser4_transaction_models "transaction models"], which include pure journaling (equivalent to ext4's data-mode journaling), pure Copy-on-Write approach (equivalent to btrfs' default) and a combined approach which heuristically alternates between the two former. ''It should be noted that reiser4 does not provide an equivalent to ext4's default journaling behavior (meta-data only).''
 +
 
 +
The other filesystems provide ordered-mode journaling, which only logs meta-data. While all journaling will return a filesystem to a valid state after a crash, data-mode journaling offers the greatest protection against corruption and data loss. There is a compromise in system performance, however, because data-mode journaling does two write operations: first to the journal and then to the disk. The trade-off between system speed and data safety should be considered when choosing the filesystem type.
 +
 
 +
=== FUSE-based file systems ===
 +
 
 +
[[Wikipedia:Filesystem in Userspace|Filesystem in Userspace]] (FUSE) is a mechanism for Unix-like operating systems that lets non-privileged users create their own file systems without editing kernel code. This is achieved by running file system code in ''user space'', while the FUSE kernel module provides only a "bridge" to the actual kernel interfaces.
 +
 
 +
Some FUSE-based file systems:
 +
 
 +
* {{App|adbfs-git|Mount an Android device filesystem.|http://collectskin.com/adbfs/|{{AUR|adbfs-git}}}}
 +
* {{App|fuseiso|Mount an ISO as a regular user.|http://sourceforge.net/projects/fuseiso/|{{Pkg|fuseiso}}}}
 +
* {{App|vdfuse|Mounting VirtualBox disk images (VDI/VMDK/VHD).|https://github.com/muflone/virtualbox-includes|{{AUR|vdfuse}}}}
 +
* {{App|xbfuse-git|Mount an Xbox (360) ISO.|http://multimedia.cx/xbfuse/|{{AUR|xbfuse-git}}}}
 +
* {{App|xmlfs|Represent an XML file as a directory structure for easy access.|https://github.com/halhen/xmlfs|{{AUR|xmlfs}}}}
 +
* {{App|[[EncFS]]|EncFS is a userspace stackable cryptographic file-system.|https://vgough.github.io/encfs/|{{Pkg|encfs}}}}
 +
* {{App|[[gitfs]]|gitfs is a FUSE file system that fully integrates with git.|https://www.presslabs.com/gitfs/|{{Aur|gitfs}}}}
 +
 
 +
See [[Wikipedia:Filesystem in Userspace#Example uses]] for more.
 +
 
 +
=== Stackable file systems ===
 +
 
 +
* {{App|[[eCryptfs]]|The Enterprise Cryptographic Filesystem is a package of disk encryption software for Linux. It is implemented as a POSIX-compliant filesystem-level encryption layer, aiming to offer functionality similar to that of GnuPG at the operating system level.|http://ecryptfs.org|{{Pkg|ecryptfs-utils}}}}
 +
 
 +
* {{App|[[overlayfs]]|OverlayFS is a filesystem service for Linux which implements a union mount for other file systems.|https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt|{{Pkg|linux}}}}
 +
 
 +
* {{App|Unionfs|Unionfs is a filesystem service for Linux, FreeBSD and NetBSD which implements a union mount for other file systems.|http://unionfs.filesystems.org/|{{pkg|linux}}}}
 +
 
 +
=== Other file systems ===
 +
 
 +
{{Expansion}}
 +
{{Style|Ambiguous section name, c.f. [https://upload.wikimedia.org/wikipedia/commons/3/30/IO_stack_of_the_Linux_kernel.svg].}}
 +
 
 +
* {{App|[[Wikipedia: SquashFS|SquashFS]]|'''SquashFS''' is a compressed read only filesystem. SquashFS compresses  files, inodes and directories, and supports block sizes up to 1 MB for greater compression.|http://squashfs.sourceforge.net/|{{Pkg|squashfs-tools}}}}
 +
 
 +
* {{App|[[Wikipedia: OrangeFS|OrangeFS]]|'''OrangeFS''' is a scale-out network file system designed for transparently accessing multi-server-based disk storage, in parallel. Has optimized MPI-IO support for parallel and distributed applications. Simplifies the use of parallel storage not only for Linux clients, but also for Windows, Hadoop, and WebDAV. POSIX-compatible. Part of Linux kernel since version 4.6. |http://www.orangefs.org/}}
 +
 
 +
== Identify existing file systems ==
 +
 
 +
To identify existing file systems, you can use [[lsblk]]:
 +
 
 +
{{hc|1=$ lsblk -f|2=
 +
NAME  FSTYPE LABEL    UUID                                MOUNTPOINT
 +
sdb                                                         
 +
└─sdb1 vfat  Transcend 4A3C-A9E9                           
 +
}}
 +
 
 +
An existing file system, if present, will be shown in the {{ic|FSTYPE}} column. If [[mount]]ed, it will appear in the {{ic|MOUNTPOINT}} column.
 +
 
 +
== Create a file system ==
 +
 
 +
File systems are usually created on a [[partition]], inside logical containers such as [[LVM]], [[RAID]] and [[dm-crypt]], or on a regular file (see [[w:Loop device]]). This section describes the partition case.
 +
 
 +
{{Note|1=File systems can be written directly to a disk, known as a [https://msdn.microsoft.com/en-us/library/windows/hardware/dn640535(v=vs.85).aspx#gpt_faq_superfloppy superfloppy] or ''partitionless disk''. Certain limitations are involved with this method, particularly if [[Arch boot process|booting]] from such a drive. See [[Btrfs#Partitionless Btrfs disk]] for an example.}}
 +
 
 +
{{Warning|
 +
* After creating a new filesystem, data previously stored on this partition can unlikely be recovered. '''Create a backup of any data you want to keep'''.
 +
*The purpose of a given partition may restrict the choice of file system. For example, an [[EFI System Partition]] must contain a FAT32 ({{ic|mkfs.vfat}}) file system, and the file system containing the {{ic|/boot}} directory must be supported by the [[:Category:Boot loaders|boot loader]].
 +
}}
 +
 
 +
Before continuing, [[lsblk|identify the device]] where the file system will be created and whether or not it is mounted. For example:
 +
 
 +
{{hc|$ lsblk -f|
 +
NAME  FSTYPE  LABEL      UUID                                MOUNTPOINT
 +
sda
 +
├─sda1                      C4DA-2C4D                           
 +
├─sda2 ext4                5b1564b2-2e2c-452c-bcfa-d1f572ae99f2 /mnt
 +
└─sda3                      56adc99b-a61e-46af-aab7-a6d07e504652
 +
}}
 +
 
 +
Mounted file systems '''must''' be [[#Unmount a file system|unmounted]] before proceeding. In the above example an existing filesystem is on {{ic|/dev/sda2}} and is mounted at {{ic|/mnt}}. It would be unmounted with:
 +
 
 +
# umount /dev/sda2
 +
 
 +
To find just mounted file systems, see [[#Listing mounted file systems]].
 +
 
 +
To create a new file system, use {{man|8|mkfs}}. See [[#Types of file systems]] for the exact type, as well as userspace utilities you may wish to install for a particular file system.
 +
 
 +
For example, to create a new file system of type [[ext4]] (common for Linux data partitions) on {{ic|/dev/''sda1''}}, run:
 +
 
 +
# mkfs.''ext4'' /dev/''sda1''
  
Individual drive partitions can be setup using one of the many different available filesystems. Each has its own advantages, disadvantages, and unique idiosyncrasies. A brief overview of supported filesystems follows; the links are to wikipedia pages that provide much more information.
+
{{Tip|
 +
* Use the {{ic|-L}} flag of ''mkfs.ext4'' to specify a [[Persistent_block_device_naming#by-label|file system label]]. ''e4label'' can be used to change the label on an existing file system.
 +
* File systems may be ''resized'' after creation, with certain limitations. For example, an [[XFS]] filesystem's size can be increased, but it cannot reduced. See [[w:Comparison_of_file_systems#Features|Resize capabilities]] and the respective file system documentation for details.}}
  
Before being formatted, a drive should be [[Partitioning|partitioned]].
+
The new file system can now be mounted to a directory of choice.
  
==Type of File Systems==
+
== Mount a filesystem ==
  
* [[Wikipedia:ext2|ext2]] '''Second Extended Filesystem''' is an established, mature GNU/Linux filesystem that is very stable. A drawback is that it does not have journaling support (see below) or barriers. Lack of journaling can result in data loss in the event of a power failure or system crash. It may also be inconvenient for root ({{ic|/}}) and {{ic|/home}} partitions because file-system checks can take a long time. An ext2 filesystem can be converted to ext3.
+
To manually mount a filesystem on a device (e.g., a partition) use {{man|8|mount}}:
* [[ext3]] '''Third Extended Filesystem''' is essentially the ext2 system with journaling support and write barriers. It is backward compatible with ext2, well tested, and extremely stable.
+
* [[ext4]] '''Fourth Extended Filesystem''' is a newer filesystem that is also compatible with ext2 and ext3. It provides support for volumes with sizes up to 1 exabyte (i.e. 1,048,576 terabytes) and files sizes up to 16 terabytes. It increases the 32,000 subdirectory limit in ext3 to 64,000. It also offers online defragmentation capability.
+
* [[Wikipedia:ReiserFS|ReiserFS]] (V3) Hans Reiser's high-performance journaling FS uses a very interesting method of data throughput based on an unconventional and creative algorithm. ReiserFS is touted as very fast, especially when dealing with many small files. ReiserFS is fast at formatting, yet comparatively slow at mounting. Quite mature and stable. ReiserFS (V3) is not being actively developed at this time. Generally regarded as a good choice for {{ic|/var}}.
+
* [[Wikipedia:JFS (file system)|JFS]] IBM's '''Journaled File System''' was the first filesystem to offer journaling. It had many years of development in the IBM AIX® operating system before being ported to GNU/Linux. JFS makes the smallest demand on CPU resources of any GNU/Linux filesystem. It is very fast at formatting, mounting, and filesystem checks (fsck). JFS offers very good all-around performance especially in conjunction with the deadline I/O scheduler. It is not as widely supported as the ext series or ReiserFS, but still very mature and stable.{{Note|The JFS filesystem cannot be shrunk by disk utilities such as '''gparted'''.}}
+
* [[Wikipedia:XFS|XFS]] is another early journaling filesystem originally developed by Silicon Graphics for the IRIX operating system and ported to GNU/Linux. It provides very fast throughput on large files and filesystems and is very fast at formatting and mounting. Comparative benchmark testing has shown it to be slower when dealing with many small files. XFS is very mature and offers online defragmentation capability.{{Note|The XFS filesystem cannot be shrunk by disk utilities such as '''gparted'''.}}
+
* [[Wikipedia:File Allocation Table#VFAT|VFAT]] or '''Virtual File Allocation Table''' is technically simple and supported by virtually all existing operating systems. This makes it a useful format for solid-state memory cards and a convenient way to share data between operating systems. VFAT supports long file names.
+
* [[Btrfs]] Also known as "Better FS", '''Btrfs''' is a new filesystem with powerful features similar to Sun/Oracle's excellent [[Wikipedia:ZFS|ZFS]]. These include snapshots, multi-disk striping and mirroring (software RAID without mdadm), checksums, incremental backup, and on-the-fly compression that can give a significant performance boost as well as save space. As of January 2011, Btrfs is considered unstable although it has been merged into the mainline kernel with an experimental status. Btrfs appears to be the future of GNU/Linux filesystems and is offered as a root filesystem option in all major distribution installers.
+
* [[Wikipedia:NILFS|NILFS2]] '''New Implementation of a Log-structured File System''' was developed by NTT. It records all data in a continuous log-like format that is only appended to and never overwritten. It is designed to reduce seek times and minimize the type of data loss that occurs after a crash with conventional Linux filesystems.
+
* [[Swap]] is the filesystem used for swap partitions.
+
* [[Wikipedia:NTFS|NTFS]] - File system used by windows. Mountable with many utilities (e.g. [[NTFS-3G]]).
+
  
===Journaling===
+
# mount ''/dev/sda1'' ''/mnt''
  
All the above filesystems with the exception of ext2 use [http://en.wikipedia.org/wiki/Journaling_file_system journaling]. Journaling provides fault-resilience by logging changes before they are committed to the filesystem. In the event of a system crash or power failure, such file systems are faster to bring back online and less likely to become corrupted. The logging takes place in a dedicated area of the filesystem.
+
This attaches the filesystem on {{ic|''/dev/sda1''}} at the directory {{ic|''/mnt''}}, making the contents of the filesystem visible. Any data that existed at {{ic|''/mnt''}} before this action is made invisible until the device is unmounted.
  
Not all journaling techniques are the same. Only ext3 and ext4 offer data-mode journaling, which logs both data and meta-data. Data-mode journaling comes with a speed penalty and is not enabled by default. The other filesystems provide ordered-mode journaling, which only logs meta-data. While all journaling will return a filesystem to a valid state after a crash, data-mode journaling offers the greatest protection against corruption and data loss. There is a compromise in system performance, however, because data-mode journaling does two write operations: first to the journal and then to the disk. The trade-off between system speed and data safety should be considered when choosing the filesystem type.
+
[[fstab]] contains information on how devices should be automatically mounted if present. See the [[fstab]] article for more information on how to modify this behavior.
  
== Format a device ==
+
If a device is specified in {{ic|/etc/fstab}} and only the device or mount point is given on the command line, that information will be used in mounting. For example, if {{ic|/etc/fstab}} contains a line indicating that {{ic|''/dev/sda1''}} should be mounted to {{ic|''/mnt''}}, then the following will automatically mount the device to that location:
{{Warning|formatting a device removes everything on it, make sure to backup everything you want to keep.}}
+
  
{{Note|the authors of this article cannot be considered responsible of any data loss, hardware deterioration or any other problem related to this article.}}
+
# mount ''/dev/sda1''
  
===Pre-requirements===
+
Or
Before starting, you need to know which name Linux gave to your device. Hard drives and USB sticks show up as {{ic|/dev/sd''x''}}, where "x" is a lowercase letter, while partitions show up as {{ic|/dev/sd''xY''}}, where "Y" is a number.
+
  
If the device you want to format is mounted, it will show up in the ''MOUNTPOINT'' column from:
+
# mount ''/mnt''
  
$ lsblk
+
''mount'' contains several options, many of which depend on the file system specified.
 +
The options can be changed, either by:
 +
* using flags on the command line with ''mount''
 +
* editing [[fstab]]
 +
* creating [[udev]] rules
 +
* [[Arch Build System|compiling the kernel yourself]]
 +
* or using filesystem-specific mount scripts (located at {{ic|/usr/bin/mount.*}}).
  
If your device is not mounted:
+
See these related articles and the article of the filesystem of interest for more information.
  
# mount /dev/sd''xY'' /some/directory
+
=== List mounted file systems ===
  
And to unmount it, you can use ''umount'' on the directory you mounted the disk on:
+
To list all mounted file systems, use {{man|8|findmnt}}:
  
  # umount /some/directory
+
  $ findmnt
  
{{note|Your device must be unmounted to format and create a new file system.}}
+
''findmnt'' takes a variety of arguments which can filter the output and show additional information. For example, it can take a device or mount point as an argument to show only information on what is specified:
  
===Step 1: delete old partitions, create new ones===
+
$ findmnt ''/dev/sda1''
  
For that you can use {{ic|fdisk}} (for MBR) or {{ic|gdisk}} (for GPT). See [[partitioning]] for more information.
+
''findmnt'' gathers information from {{ic|/etc/fstab}}, {{ic|/etc/mtab}}, and {{ic|/proc/self/mounts}}.
  
# fdisk /dev/''<device>''
+
=== Umount a file system ===
  
{{Note|Enter {{ic|m}} to display the available commands.}}
+
To unmount a file system use {{man|8|umount}}. Either the device containting the file system or the mount point can be specified:
  
===Step 2: create the new file system===
+
# umount ''/dev/sda1''
==== In console====
+
To create a file system you just have to use {{ic|mkfs}}:
+
  
# mkfs -t ext4 /dev/''<partition>''
+
Or
  
As {{ic|mkfs}} is just a unified front-end for the different {{ic|mkfs.''fstype''}} tools, you need to install the packages providing these tools for each filesystem you want to use:
+
# umount ''/mnt''
  
* {{pkg|btrfs-progs}} provides {{ic|btrfs}}
+
== See also ==
* {{pkg|e2fsprogs}} provides {{ic|ext2}}, {{ic|ext3}} and {{ic|ext4}}
+
* {{pkg|jfsutils}} provides {{ic|jfs}}
+
* {{pkg|ntfsprogs}} provides {{ic|ntfs}}
+
* {{pkg|reiserfsprogs}} provides {{ic|reiserfs}}
+
* {{pkg|dosfstools}} provides {{ic|vfat}} (also known as {{ic|msdos}})
+
* {{pkg|xfsprogs}} provides {{ic|xfs}}
+
* {{pkg|nilfs-utils}} provides {{ic|nilfs2}}
+
  
=== GUI tools ===
+
* {{man|5|filesystems}}
There are several GUI tools for partition management:
+
* [https://www.kernel.org/doc/Documentation/filesystems/ Documentation of file systems supported by linux]
*[http://gparted.sourceforge.net/ GParted] (GTK) is available in extra
+
* [[Wikipedia:File systems]]
* {{pkg|gnome-disk-utility}}
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* [[Wikipedia:Mount (Unix)]]
*[http://www.kde-apps.org/content/show.php/KDE+Partition+Manager?content=89595 KDE Partition Manager] (KDE/Qt) is available in [[AUR]]
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Latest revision as of 12:14, 30 November 2016

From Wikipedia:

In computing, a file system (or filesystem) is used to control how data is stored and retrieved. Without a file system, information placed in a storage medium would be one large body of data with no way to tell where one piece of information stops and the next begins. By separating the data into pieces and giving each piece a name, the information is easily isolated and identified.
Taking its name from the way paper-based information systems are named, each group of data is called a "file". The structure and logic rules used to manage the groups of information and their names is called a "file system".

Individual drive partitions can be setup using one of the many different available filesystems. Each has its own advantages, disadvantages, and unique idiosyncrasies. A brief overview of supported filesystems follows; the links are to Wikipedia pages that provide much more information.

Types of file systems

See filesystems(5) for a general overview, and Wikipedia:Comparison of file systems for a detailed feature comparison. File systems supported by the kernel are listed in /proc/filesystems.

File system Creation command Userspace utilities Archiso [1] Kernel documentation [2] Notes
Btrfs mkfs.btrfs(8) btrfs-progs Yes btrfs.txt Stability status
VFAT mkfs.vfat(8) dosfstools Yes vfat.txt
exFAT mkfs.exfat(8) exfat-utils Optional N/A (FUSE-based)
F2FS mkfs.f2fs(8) f2fs-tools Yes f2fs.txt Flash-based devices
ext3 mke2fs(8) e2fsprogs Yes (base) ext3.txt
ext4 mke2fs(8) e2fsprogs Yes (base) ext4.txt
HFS mkfs.hfsplus(8) hfsprogs Optional hfs.txt macOS file system
JFS mkfs.jfs(8) jfsutils Yes (base) jfs.txt
NILFS2 mkfs.nilfs2(8) nilfs-utils Yes nilfs2.txt
NTFS mkfs.ntfs(8) ntfs-3g Yes N/A (FUSE-based) Windows file system
Reiser4 mkfs.reiser4(8) reiser4progsAUR No
ReiserFS mkfs.reiserfs(8) reiserfsprogs Yes (base)
XFS mkfs.xfs(8) xfsprogs Yes (base)

xfs.txt
xfs-delayed-logging-design.txt
xfs-self-describing-metadata.txt

ZFS zfs-linuxAUR No N/A (OpenZFS port)
Note: The kernel has its own NTFS driver (see ntfs.txt), but it has limited support for writing files.

Journaling

All the above filesystems with the exception of ext2, FAT16/32, use journaling. Journaling provides fault-resilience by logging changes before they are committed to the filesystem. In the event of a system crash or power failure, such file systems are faster to bring back online and less likely to become corrupted. The logging takes place in a dedicated area of the filesystem.

Not all journaling techniques are the same. Ext3 and ext4 offer data-mode journaling, which logs both data and meta-data, as well as possibility to journal only meta-data changes. Data-mode journaling comes with a speed penalty and is not enabled by default. In the same vein, Reiser4 offers so-called "transaction models", which include pure journaling (equivalent to ext4's data-mode journaling), pure Copy-on-Write approach (equivalent to btrfs' default) and a combined approach which heuristically alternates between the two former. It should be noted that reiser4 does not provide an equivalent to ext4's default journaling behavior (meta-data only).

The other filesystems provide ordered-mode journaling, which only logs meta-data. While all journaling will return a filesystem to a valid state after a crash, data-mode journaling offers the greatest protection against corruption and data loss. There is a compromise in system performance, however, because data-mode journaling does two write operations: first to the journal and then to the disk. The trade-off between system speed and data safety should be considered when choosing the filesystem type.

FUSE-based file systems

Filesystem in Userspace (FUSE) is a mechanism for Unix-like operating systems that lets non-privileged users create their own file systems without editing kernel code. This is achieved by running file system code in user space, while the FUSE kernel module provides only a "bridge" to the actual kernel interfaces.

Some FUSE-based file systems:

  • adbfs-git — Mount an Android device filesystem.
http://collectskin.com/adbfs/ || adbfs-gitAUR
  • fuseiso — Mount an ISO as a regular user.
http://sourceforge.net/projects/fuseiso/ || fuseiso
  • vdfuse — Mounting VirtualBox disk images (VDI/VMDK/VHD).
https://github.com/muflone/virtualbox-includes || vdfuseAUR
  • xbfuse-git — Mount an Xbox (360) ISO.
http://multimedia.cx/xbfuse/ || xbfuse-gitAUR
  • xmlfs — Represent an XML file as a directory structure for easy access.
https://github.com/halhen/xmlfs || xmlfsAUR
  • EncFS — EncFS is a userspace stackable cryptographic file-system.
https://vgough.github.io/encfs/ || encfs
  • gitfs — gitfs is a FUSE file system that fully integrates with git.
https://www.presslabs.com/gitfs/ || gitfsAUR

See Wikipedia:Filesystem in Userspace#Example uses for more.

Stackable file systems

  • eCryptfs — The Enterprise Cryptographic Filesystem is a package of disk encryption software for Linux. It is implemented as a POSIX-compliant filesystem-level encryption layer, aiming to offer functionality similar to that of GnuPG at the operating system level.
http://ecryptfs.org || ecryptfs-utils
  • overlayfs — OverlayFS is a filesystem service for Linux which implements a union mount for other file systems.
https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt || linux
  • Unionfs — Unionfs is a filesystem service for Linux, FreeBSD and NetBSD which implements a union mount for other file systems.
http://unionfs.filesystems.org/ || linux

Other file systems

Tango-view-fullscreen.pngThis article or section needs expansion.Tango-view-fullscreen.png

Reason: please use the first argument of the template to provide a brief explanation. (Discuss in Talk:File systems#)

Tango-edit-clear.pngThis article or section needs language, wiki syntax or style improvements.Tango-edit-clear.png

Reason: Ambiguous section name, c.f. [3]. (Discuss in Talk:File systems#)
  • SquashFSSquashFS is a compressed read only filesystem. SquashFS compresses files, inodes and directories, and supports block sizes up to 1 MB for greater compression.
http://squashfs.sourceforge.net/ || squashfs-tools
  • OrangeFSOrangeFS is a scale-out network file system designed for transparently accessing multi-server-based disk storage, in parallel. Has optimized MPI-IO support for parallel and distributed applications. Simplifies the use of parallel storage not only for Linux clients, but also for Windows, Hadoop, and WebDAV. POSIX-compatible. Part of Linux kernel since version 4.6.
http://www.orangefs.org/ || not packaged? search in AUR

Identify existing file systems

To identify existing file systems, you can use lsblk:

$ lsblk -f
NAME   FSTYPE LABEL     UUID                                 MOUNTPOINT
sdb                                                          
└─sdb1 vfat   Transcend 4A3C-A9E9

An existing file system, if present, will be shown in the FSTYPE column. If mounted, it will appear in the MOUNTPOINT column.

Create a file system

File systems are usually created on a partition, inside logical containers such as LVM, RAID and dm-crypt, or on a regular file (see w:Loop device). This section describes the partition case.

Note: File systems can be written directly to a disk, known as a superfloppy or partitionless disk. Certain limitations are involved with this method, particularly if booting from such a drive. See Btrfs#Partitionless Btrfs disk for an example.
Warning:
  • After creating a new filesystem, data previously stored on this partition can unlikely be recovered. Create a backup of any data you want to keep.
  • The purpose of a given partition may restrict the choice of file system. For example, an EFI System Partition must contain a FAT32 (mkfs.vfat) file system, and the file system containing the /boot directory must be supported by the boot loader.

Before continuing, identify the device where the file system will be created and whether or not it is mounted. For example:

$ lsblk -f
NAME   FSTYPE   LABEL       UUID                                 MOUNTPOINT
sda
├─sda1                      C4DA-2C4D                            
├─sda2 ext4                 5b1564b2-2e2c-452c-bcfa-d1f572ae99f2 /mnt
└─sda3                      56adc99b-a61e-46af-aab7-a6d07e504652 

Mounted file systems must be unmounted before proceeding. In the above example an existing filesystem is on /dev/sda2 and is mounted at /mnt. It would be unmounted with:

# umount /dev/sda2

To find just mounted file systems, see #Listing mounted file systems.

To create a new file system, use mkfs(8). See #Types of file systems for the exact type, as well as userspace utilities you may wish to install for a particular file system.

For example, to create a new file system of type ext4 (common for Linux data partitions) on /dev/sda1, run:

# mkfs.ext4 /dev/sda1
Tip:
  • Use the -L flag of mkfs.ext4 to specify a file system label. e4label can be used to change the label on an existing file system.
  • File systems may be resized after creation, with certain limitations. For example, an XFS filesystem's size can be increased, but it cannot reduced. See Resize capabilities and the respective file system documentation for details.

The new file system can now be mounted to a directory of choice.

Mount a filesystem

To manually mount a filesystem on a device (e.g., a partition) use mount(8):

# mount /dev/sda1 /mnt

This attaches the filesystem on /dev/sda1 at the directory /mnt, making the contents of the filesystem visible. Any data that existed at /mnt before this action is made invisible until the device is unmounted.

fstab contains information on how devices should be automatically mounted if present. See the fstab article for more information on how to modify this behavior.

If a device is specified in /etc/fstab and only the device or mount point is given on the command line, that information will be used in mounting. For example, if /etc/fstab contains a line indicating that /dev/sda1 should be mounted to /mnt, then the following will automatically mount the device to that location:

# mount /dev/sda1

Or

# mount /mnt

mount contains several options, many of which depend on the file system specified. The options can be changed, either by:

See these related articles and the article of the filesystem of interest for more information.

List mounted file systems

To list all mounted file systems, use findmnt(8):

$ findmnt

findmnt takes a variety of arguments which can filter the output and show additional information. For example, it can take a device or mount point as an argument to show only information on what is specified:

$ findmnt /dev/sda1

findmnt gathers information from /etc/fstab, /etc/mtab, and /proc/self/mounts.

Umount a file system

To unmount a file system use umount(8). Either the device containting the file system or the mount point can be specified:

# umount /dev/sda1

Or

# umount /mnt

See also