X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=misc%2Fmke2fs.8.in;h=429ceba3026850d721e43ef378a65c000b796d93;hb=4ea40c0bc20c6e5a9a6ac141215ab7a0b942ea7a;hp=57e3940b549daf71942c0a3341e2bc35661a793c;hpb=8d6417498c96c6877ed42da29991c82961e1bf15;p=tools%2Fe2fsprogs.git diff --git a/misc/mke2fs.8.in b/misc/mke2fs.8.in index 57e3940..429ceba 100644 --- a/misc/mke2fs.8.in +++ b/misc/mke2fs.8.in @@ -1,15 +1,15 @@ .\" -*- nroff -*- .\" Copyright 1993, 1994, 1995 by Theodore Ts'o. All Rights Reserved. .\" This file may be copied under the terms of the GNU Public License. -.\" +.\" .TH MKE2FS 8 "@E2FSPROGS_MONTH@ @E2FSPROGS_YEAR@" "E2fsprogs version @E2FSPROGS_VERSION@" .SH NAME -mke2fs \- create a Linux second extended file system +mke2fs \- create an ext2/ext3/ext4 filesystem .SH SYNOPSIS .B mke2fs [ .B \-c -| +| .B \-l .I filename ] @@ -18,14 +18,33 @@ mke2fs \- create a Linux second extended file system .I block-size ] [ +.B \-d +.I root-directory +] +[ +.B \-D +] +[ .B \-f .I fragment-size ] [ +.B \-g +.I blocks-per-group +] +[ +.B \-G +.I number-of-groups +] +[ .B \-i .I bytes-per-inode ] [ +.B \-I +.I inode-size +] +[ .B \-j ] [ @@ -37,7 +56,7 @@ mke2fs \- create a Linux second extended file system .I number-of-inodes ] [ -.B -n +.B \-n ] [ .B \-m @@ -48,8 +67,8 @@ mke2fs \- create a Linux second extended file system .I creator-os ] [ -.B \-O -.IR feature [,...] +.B \-O +[^]\fIfeature\fR[,...] ] [ .B \-q @@ -59,8 +78,8 @@ mke2fs \- create a Linux second extended file system .I fs-revision-level ] [ -.B \-R -.I raid-options +.B \-E +.I extended-options ] [ .B \-v @@ -80,15 +99,31 @@ mke2fs \- create a Linux second extended file system .B \-S ] [ +.B \-t +.I fs-type +] +[ .B \-T -.I filesystem-type +.I usage-type +] +[ +.B \-U +.I UUID ] [ .B \-V ] +[ +.B \-e +.I errors-behavior +] +[ +.B \-z +.I undo_file +] .I device [ -.I blocks-count +.I fs-size ] @JDEV@.sp @JDEV@.B "mke2fs \-O journal_dev" @@ -115,59 +150,327 @@ mke2fs \- create a Linux second extended file system @JDEV@.B \-v @JDEV@] @JDEV@.I external-journal +@JDEV@[ +@JDEV@.I fs-size +@JDEV@] .SH DESCRIPTION .B mke2fs -is used to create a Linux second extended file system on a device (usually -a disk partition). -.I device -is the special file corresponding to the device (e.g -.IR /dev/hdXX ). -.I blocks-count -is the number of blocks on the device. If omitted, +is used to create an ext2, ext3, or ext4 filesystem, usually in a disk +partition (or file) named by +.IR device . +.PP +The file system size is specified by +.IR fs-size . +If +.I fs-size +does not have a suffix, it is interpreted as power-of-two kilobytes, +unless the +.B \-b +.I blocksize +option is specified, in which case +.I fs-size +is interpreted as the number of +.I blocksize +blocks. If the fs-size is suffixed by 'k', 'm', 'g', 't' +(either upper-case or lower-case), then it is interpreted in +power-of-two kilobytes, megabytes, gigabytes, terabytes, etc. +If +.I fs-size +is omitted, .B mke2fs -automagically figures the file system size. +will create the file system based on the device size. +.PP +If +.B mke2fs +is run as +.B mkfs.XXX +(i.e., +.BR mkfs.ext2 , +.BR mkfs.ext3 , +or +.BR mkfs.ext4 ) +the option +.B \-t +.I XXX +is implied; so +.B mkfs.ext3 +will create a file system for use with ext3, +.B mkfs.ext4 +will create a file system for use with ext4, and so on. +.PP +The defaults of the parameters for the newly created filesystem, if not +overridden by the options listed below, are controlled by the +.B /etc/mke2fs.conf +configuration file. See the +.BR mke2fs.conf (5) +manual page for more details. .SH OPTIONS .TP .BI \-b " block-size" -Specify the size of blocks in bytes. Valid block size vales are 1024, +Specify the size of blocks in bytes. Valid block-size values are 1024, 2048 and 4096 bytes per block. If omitted, -.B mke2fs -block-size is determined by the file system size and the expected usage -of the filesystem (see the +block-size is heuristically determined by the filesystem size and +the expected usage of the filesystem (see the .B \-T -option). +option). If +.I block-size +is preceded by a negative sign ('-'), then +.B mke2fs +will use heuristics to determine the +appropriate block size, with the constraint that the block size will be +at least +.I block-size +bytes. This is useful for certain hardware devices which require that +the blocksize be a multiple of 2k. .TP .B \-c -Check the device for bad blocks before creating the file system, using a -fast read-only test. +Check the device for bad blocks before creating the file system. If +this option is specified twice, then a slower read-write +test is used instead of a fast read-only test. +.TP +.B \-C " cluster-size" +Specify the size of cluster in bytes for filesystems using the bigalloc +feature. Valid cluster-size values are from 2048 to 256M bytes per +cluster. This can only be specified if the bigalloc feature is +enabled. (See the +.B ext4 (5) +man page for more details about bigalloc.) The default cluster size if +bigalloc is enabled is 16 times the block size. +.TP +.BI \-d " root-directory" +Copy the contents of the given directory into the root directory of the +filesystem. +.TP +.B \-D +Use direct I/O when writing to the disk. This avoids mke2fs dirtying a +lot of buffer cache memory, which may impact other applications running +on a busy server. This option will cause mke2fs to run much more +slowly, however, so there is a tradeoff to using direct I/O. +.TP +.BI \-e " error-behavior" +Change the behavior of the kernel code when errors are detected. +In all cases, a filesystem error will cause +.BR e2fsck (8) +to check the filesystem on the next boot. +.I error-behavior +can be one of the following: +.RS 1.2i +.TP 1.2i +.B continue +Continue normal execution. +.TP +.B remount-ro +Remount filesystem read-only. +.TP +.B panic +Cause a kernel panic. +.RE +.TP +.BI \-E " extended-options" +Set extended options for the filesystem. Extended options are comma +separated, and may take an argument using the equals ('=') sign. The +.B \-E +option used to be +.B \-R +in earlier versions of +.BR mke2fs . +The +.B \-R +option is still accepted for backwards compatibility, but is deprecated. +The following extended options are supported: +.RS 1.2i +.TP +.BI mmp_update_interval= interval +Adjust the initial MMP update interval to +.I interval +seconds. Specifying an +.I interval +of 0 means to use the default interval. The specified interval must +be less than 300 seconds. Requires that the +.B mmp +feature be enabled. +.TP +.BI stride= stride-size +Configure the filesystem for a RAID array with +.I stride-size +filesystem blocks. This is the number of blocks read or written to disk +before moving to the next disk, which is sometimes referred to as the +.I chunk size. +This mostly affects placement of filesystem metadata like bitmaps at +.B mke2fs +time to avoid placing them on a single disk, which can hurt performance. +It may also be used by the block allocator. +.TP +.BI stripe_width= stripe-width +Configure the filesystem for a RAID array with +.I stripe-width +filesystem blocks per stripe. This is typically stride-size * N, where +N is the number of data-bearing disks in the RAID (e.g. for RAID 5 there is one +parity disk, so N will be the number of disks in the array minus 1). +This allows the block allocator to prevent read-modify-write of the +parity in a RAID stripe if possible when the data is written. +.TP +.BI offset= offset +Create the filesystem at an offset from the beginning of the device or +file. This can be useful when creating disk images for virtual machines. +.TP +.BI resize= max-online-resize +Reserve enough space so that the block group descriptor table can grow +to support a filesystem that has +.I max-online-resize +blocks. +.TP +.B lazy_itable_init\fR[\fB= \fI<0 to disable, 1 to enable>\fR] +If enabled and the uninit_bg feature is enabled, the inode table will +not be fully initialized by +.BR mke2fs . +This speeds up filesystem +initialization noticeably, but it requires the kernel to finish +initializing the filesystem in the background when the filesystem is +first mounted. If the option value is omitted, it defaults to 1 to +enable lazy inode table zeroing. +.TP +.B lazy_journal_init\fR[\fB= \fI<0 to disable, 1 to enable>\fR] +If enabled, the journal inode will not be fully zeroed out by +.BR mke2fs . +This speeds up filesystem initialization noticeably, but carries some +small risk if the system crashes before the journal has been overwritten +entirely one time. If the option value is omitted, it defaults to 1 to +enable lazy journal inode zeroing. +.TP +.BI num_backup_sb= <0|1|2> +If the +.B sparse_super2 +file system feature is enabled this option controls whether there will +be 0, 1, or 2 backup superblocks created in the file system. +.TP +.B packed_meta_blocks\fR[\fB= \fI<0 to disable, 1 to enable>\fR] +Place the allocation bitmaps and the inode table at the beginning of the +disk. This option requires that the flex_bg file system feature to be +enabled in order for it to have effect, and will also create the journal +at the beginning of the file system. This option is useful for flash +devices that use SLC flash at the beginning of the disk. +It also maximizes the range of contiguous data blocks, which +can be useful for certain specialized use cases, such as supported +Shingled Drives. +.TP +.BI root_owner [=uid:gid] +Specify the numeric user and group ID of the root directory. If no UID:GID +is specified, use the user and group ID of the user running \fBmke2fs\fR. +In \fBmke2fs\fR 1.42 and earlier the UID and GID of the root directory were +set by default to the UID and GID of the user running the mke2fs command. +The \fBroot_owner=\fR option allows explicitly specifying these values, +and avoid side-effects for users that do not expect the contents of the +filesystem to change based on the user running \fBmke2fs\fR. +.TP +.B test_fs +Set a flag in the filesystem superblock indicating that it may be +mounted using experimental kernel code, such as the ext4dev filesystem. +.TP +.BI discard +Attempt to discard blocks at mkfs time (discarding blocks initially is useful +on solid state devices and sparse / thin-provisioned storage). When the device +advertises that discard also zeroes data (any subsequent read after the discard +and before write returns zero), then mark all not-yet-zeroed inode tables as +zeroed. This significantly speeds up filesystem initialization. This is set +as default. +.TP +.BI nodiscard +Do not attempt to discard blocks at mkfs time. +.TP +.BI quotatype +Specify which quota type ('usr' or 'grp') is to be +initialized. This option has effect only if the +.B quota +feature is set. Without this extended option, the default +behavior is to initialize both user and group quotas. +.RE .TP .BI \-f " fragment-size" Specify the size of fragments in bytes. .TP .B \-F -Force +Force +.B mke2fs +to create a filesystem, even if the specified device is not a partition +on a block special device, or if other parameters do not make sense. +In order to force .B mke2fs -to run, even if the specified device is not a -block special device, or appears to be mounted. +to create a filesystem even if the filesystem appears to be in use +or is mounted (a truly dangerous thing to do), this option must be +specified twice. +.TP +.BI \-g " blocks-per-group" +Specify the number of blocks in a block group. There is generally no +reason for the user to ever set this parameter, as the default is optimal +for the filesystem. (For administrators who are creating +filesystems on RAID arrays, it is preferable to use the +.I stride +RAID parameter as part of the +.B \-E +option rather than manipulating the number of blocks per group.) +This option is generally used by developers who +are developing test cases. +.IP +If the bigalloc feature is enabled, the +.B \-g +option will specify the number of clusters in a block group. +.TP +.BI \-G " number-of-groups" +Specify the number of block groups that will be packed together to +create a larger virtual block group (or "flex_bg group") in an +ext4 filesystem. This improves meta-data locality and performance +on meta-data heavy workloads. The number of groups must be a power +of 2 and may only be specified if the +.B flex_bg +filesystem feature is enabled. .TP .BI \-i " bytes-per-inode" -Specify the bytes/inode ratio. +Specify the bytes/inode ratio. .B mke2fs creates an inode for every .I bytes-per-inode -bytes of space on the disk. The larger the +bytes of space on the disk. The larger the .I bytes-per-inode ratio, the fewer inodes will be created. This value generally shouldn't -be smaller than the blocksize of the filesystem, since then too many -inodes will be made. Be warned that is not possible to expand the number -of inodes on a filesystem after it is created, so be careful deciding the -correct value for this parameter. -.TP +be smaller than the blocksize of the filesystem, since in that case more +inodes would be made than can ever be used. Be warned that it is not +possible to change this ratio on a filesystem after it is created, so be +careful deciding the correct value for this parameter. Note that resizing +a filesystem changes the numer of inodes to maintain this ratio. +.TP +.BI \-I " inode-size" +Specify the size of each inode in bytes. +The +.I inode-size +value must be a power of 2 larger or equal to 128. The larger the +.I inode-size +the more space the inode table will consume, and this reduces the usable +space in the filesystem and can also negatively impact performance. +It is not +possible to change this value after the filesystem is created. +.IP +In kernels after 2.6.10 and some +earlier vendor kernels it is possible to utilize inodes larger than +128 bytes to store +extended attributes for improved performance. +Extended attributes +stored in large inodes are not visible with older kernels, and such +filesystems will not be mountable with 2.4 kernels at all. +.IP +The default inode size is controlled by the +.BR mke2fs.conf (5) +file. In the +.B mke2fs.conf +file shipped with e2fsprogs, the default inode size is 256 bytes for +most file systems, except for small file systems where the inode size +will be 128 bytes. +.TP .B \-j Create the filesystem with an ext3 journal. If the .B \-J option is not specified, the default journal parameters will be used to -create an appropriately sized journal (given the size of the filesystem) +create an appropriately sized journal (given the size of the filesystem) stored within the filesystem. Note that you must be using a kernel which has ext3 support in order to actually make use of the journal. .TP @@ -179,13 +482,20 @@ The following journal options are supported: .RS 1.2i .TP .BI size= journal-size -Create a journal stored in the filesystem of size -.I journal-size +Create an internal journal (i.e., stored inside the filesystem) of size +.I journal-size megabytes. -The size of the journal must be at least 1024 filesystem blocks -(i.e., 1MB if using 1k blocks, 4MB if using 4k blocks, etc.) -and may be no more than 102,400 filesystem blocks. -The journal must fit within the newly created filesystem. +The size of the journal must be at least 1024 filesystem blocks +(i.e., 1MB if using 1k blocks, 4MB if using 4k blocks, etc.) +and may be no more than 10,240,000 filesystem blocks or half the total +file system size (whichever is smaller) +.TP +.BI location =journal-location +Specify the location of the journal. The argument +.I journal-location +can either be specified as a block number, or if the number has a units +suffix (e.g., 'M', 'G', etc.) interpret it as the offset from the +beginning of the file system. @JDEV@.TP @JDEV@.BI device= external-journal @JDEV@Attach the filesystem to the journal block device located on @@ -193,13 +503,32 @@ The journal must fit within the newly created filesystem. @JDEV@The external @JDEV@journal must already have been created using the command @JDEV@.IP -@JDEV@.B mke2fs -O journal_dev -@JDEV@.IR external-journal +@JDEV@.B mke2fs -O journal_dev +@JDEV@.I external-journal @JDEV@.IP @JDEV@Note that @JDEV@.I external-journal @JDEV@must have been created with the @JDEV@same block size as the new filesystem. +@JDEV@In addition, while there is support for attaching +@JDEV@multiple filesystems to a single external journal, +@JDEV@the Linux kernel and +@JDEV@.BR e2fsck (8) +@JDEV@do not currently support shared external journals yet. +@JDEV@.IP +@JDEV@Instead of specifying a device name directly, +@JDEV@.I external-journal +@JDEV@can also be specified by either +@JDEV@.BI LABEL= label +@JDEV@or +@JDEV@.BI UUID= UUID +@JDEV@to locate the external journal by either the volume label or UUID +@JDEV@stored in the ext2 superblock at the start of the journal. Use +@JDEV@.BR dumpe2fs (8) +@JDEV@to display a journal device's volume label and UUID. See also the +@JDEV@.B -L +@JDEV@option of +@JDEV@.BR tune2fs (8). .RE @JDEV@.IP @JDEV@Only one of the @@ -209,146 +538,253 @@ The journal must fit within the newly created filesystem. .BI \-l " filename" Read the bad blocks list from .IR filename . +Note that the block numbers in the bad block list must be generated +using the same block size as used by +.BR mke2fs . +As a result, the +.B \-c +option to +.B mke2fs +is a much simpler and less error-prone method of checking a disk for bad +blocks before formatting it, as +.B mke2fs +will automatically pass the correct parameters to the +.B badblocks +program. .TP -.B \-L -Set the volume label for the filesystem. +.BI \-L " new-volume-label" +Set the volume label for the filesystem to +.IR new-volume-label . +The maximum length of the +volume label is 16 bytes. .TP .BI \-m " reserved-blocks-percentage" -Specify the percentage of the filesystem blocks reserved for -the super-user. This value defaults to 5%. +Specify the percentage of the filesystem blocks reserved for +the super-user. This avoids fragmentation, and allows root-owned +daemons, such as +.BR syslogd (8), +to continue to function correctly after non-privileged processes are +prevented from writing to the filesystem. The default percentage +is 5%. .TP -.B \-M -Set the last mounted directory for the filesystem. This might be useful -for the sake of utilities that key off of the last mounted directory to -determine where the filesytem should be mounted. +.BI \-M " last-mounted-directory" +Set the last mounted directory for the filesystem. This might be useful +for the sake of utilities that key off of the last mounted directory to +determine where the filesystem should be mounted. .TP .B \-n -causes mke2fs to not actually create a filesystem, but display what it -would do if it were to create a filesystem. +Causes +.B mke2fs +to not actually create a filesystem, but display what it +would do if it were to create a filesystem. This can be used to +determine the location of the backup superblocks for a particular +filesystem, so long as the +.B mke2fs +parameters that were passed when the +filesystem was originally created are used again. (With the +.B \-n +option added, of course!) .TP .BI \-N " number-of-inodes" -overrides the default calculation of the number of inodes that should be -reserved for the filesystem (which is based on the number of blocks and -the +Overrides the default calculation of the number of inodes that should be +reserved for the filesystem (which is based on the number of blocks and +the .I bytes-per-inode -ratio). This allows the user to specify the number +ratio). This allows the user to specify the number of desired inodes directly. .TP .BI \-o " creator-os" -Manually override the default value of the "creator os" field of the -filesystem. Normally the creator field is set by default to the native OS -of the -.B mke2fs -executable. -.TP -.B "\-O \fIfeature\fR[,...]" -Create filesystem with given features (filesystem options). -Currently, the -.B sparse_super -and -.B filetype -features are turned on by default unless +Overrides the default value of the "creator operating system" field of the +filesystem. The creator field is set by default to the name of the OS the .B mke2fs -is run on a system with a pre-2.2 Linux kernel. +executable was compiled for. +.TP +.B "\-O \fR[^]\fIfeature\fR[,...]" +Create a filesystem with the given features (filesystem options), +overriding the default filesystem options. The features that are +enabled by default are specified by the +.I base_features +relation, either in the +.I [defaults] +section in the +.B /etc/mke2fs.conf +configuration file, +or in the +.I [fs_types] +subsections for the usage types as specified by the +.B \-T +option, further modified by the +.I features +relation found in the +.I [fs_types] +subsections for the filesystem and usage types. See the +.BR mke2fs.conf (5) +manual page for more details. +The filesystem type-specific configuration setting found in the +.I [fs_types] +section will override the global default found in +.IR [defaults] . .sp -.B Warning: -Linux kernels before 2.0.39 and many 2.1 series kernels do not support -filesystems that use any of these features. Filesystems that -may need to mounted on pre-2.2 kernels should be created with -.B "\-O none" -(or -.B "\-r 0" -for 1.2 kernels) which will disable these features, even if -.B mke2fs -is run on a system which can support them. +The filesystem feature set will be further edited +using either the feature set specified by this option, +or if this option is not given, by the +.I default_features +relation for the filesystem type being created, or in the +.I [defaults] +section of the configuration file. .sp -The following filesystem options are supported: -.RS 1.2i +The filesystem feature set is comprised of a list of features, separated +by commas, that are to be enabled. To disable a feature, simply +prefix the feature name with a caret ('^') character. +Features with dependencies will not be removed successfully. +The pseudo-filesystem feature "none" will clear all filesystem features. .TP -.B sparse_super -Create a filesystem with fewer superblock backup copies -(saves space on large filesystems). -.TP -.B filetype -Store file type information in directory entries. -.TP -.B has_journal -Create an ext3 journal (as if using the -.B \-j -option). -@JDEV@.TP -@JDEV@.B journal_dev -@JDEV@Create an external ext3 journal on the given device -@JDEV@instead of a regular ext2 filesystem. -@JDEV@Note that -@JDEV@.I external-journal -@JDEV@must be created with the same -@JDEV@block size as the filesystems that will be using it. -.RE +For more information about the features which can be set, please see +the manual page +.BR ext4 (5). .TP .B \-q -Quiet execution. Useful if +Quiet execution. Useful if .B mke2fs is run in a script. .TP .BI \-r " revision" Set the filesystem revision for the new filesystem. Note that 1.2 -kernels only support revision 0 filesystems. The default is to +kernels only support revision 0 filesystems. The default is to create revision 1 filesystems. .TP -.BI \-R " raid-options" -Set raid-related options for the filesystem. Raid options are comma -separated, and may take an argument using the equals ('=') sign. The -following options are supported: -.RS 1.2i -.TP -.BI stride= stripe-size -Configure the filesystem for a RAID array with -.I stripe-size -filesystem blocks per stripe. -.RE -.TP .B \-S -Write superblock and group descriptors only. This is useful if all of +Write superblock and group descriptors only. This is an extreme +measure to be taken only in the very unlikely case that all of the superblock and backup superblocks are corrupted, and a last-ditch -recovery method is desired. It causes +recovery method is desired by experienced users. It causes .B mke2fs -to reinitialize the -superblock and group descriptors, while not touching the inode table -and the block and inode bitmaps. The +to reinitialize the superblock and group descriptors, while not +touching the inode table and the block and inode bitmaps. The .B e2fsck program should be run immediately after this option is used, and there -is no guarantee that any data will be salvageable. It is critical to -specify the correct filesystem blocksize when using this option, -or there is no chance of recovery. +is no guarantee that any data will be salvageable. Due to the wide +variety of possible options to +.BR mke2fs +that affect the on-disk layout, is critical to specify exactly the same +the same format options, such as blocksize, fs-type, feature flags, and +other tunables when using this option, or the filesystem will be further +corrupted. In some cases, such as filesystems that have been resized, +or have had features enabled after format time, it is impossible to +overwrite all of the superblocks corretly, and at least some filesystem +corruption will occur. It is best to run this on a full copy of the +filesystem so other options can be tried if this doesn't work. .\" .TP .\" .BI \-t " test" .\" Check the device for bad blocks before creating the file system .\" using the specified test. .TP -.BI \-T " fs-type" -Specify how the filesystem is going to be used, so that mke2fs can -chose optimal filesystem parameters for that use. The supported -filesystem types are: -.RS 1.2i -.TP 1.2i -news -one inode per 4kb block +.BI \-t " fs-type" +Specify the filesystem type (i.e., ext2, ext3, ext4, etc.) that is +to be created. +If this option is not specified, +.B mke2fs +will pick a default either via how +the command was run (for example, using a name of the form mkfs.ext2, +mkfs.ext3, etc.) or via a default as defined by the +.B /etc/mke2fs.conf +file. This option controls which filesystem options are used by +default, based on the +.B fstypes +configuration stanza in +.BR /etc/mke2fs.conf . +.sp +If the +.B \-O +option is used to explicitly add or remove filesystem options that +should be set in the newly created filesystem, the +resulting filesystem may not be supported by the requested +.IR fs-type . +(e.g., "\fBmke2fs \-t ext3 \-O extent /dev/sdXX\fR" will create a +filesystem that is not supported by the ext3 implementation as found in +the Linux kernel; and "\fBmke2fs \-t ext3 \-O ^has_journal /dev/hdXX\fR" +will create a filesystem that does not have a journal and hence will not +be supported by the ext3 filesystem code in the Linux kernel.) .TP -largefile -one inode per megabyte +.BI \-T " usage-type[,...]" +Specify how the filesystem is going to be used, so that +.B mke2fs +can choose optimal filesystem parameters for that use. The usage +types that are supported are defined in the configuration file +.BR /etc/mke2fs.conf . +The user may specify one or more usage types +using a comma separated list. +.sp +If this option is is not specified, +.B mke2fs +will pick a single default usage type based on the size of the filesystem to +be created. If the filesystem size is less than 3 megabytes, +.B mke2fs +will use the filesystem type +.IR floppy . +If the filesystem size is greater than or equal to 3 but less than +512 megabytes, +.BR mke2fs (8) +will use the filesystem type +.IR small . +If the filesystem size is greater than or equal to 4 terabytes but less than +16 terabytes, +.BR mke2fs (8) +will use the filesystem type +.IR big . +If the filesystem size is greater than or equal to 16 terabytes, +.BR mke2fs (8) +will use the filesystem type +.IR huge . +Otherwise, +.BR mke2fs (8) +will use the default filesystem type +.IR default . .TP -largefile4 -one inode per 4 megabytes -.RE +.BI \-U " UUID" +Create the filesystem with the specified UUID. .TP .B \-v Verbose execution. .TP .B \-V -Print the version number of +Print the version number of .B mke2fs and exit. +.TP +.BI \-z " undo_file" +Before overwriting a file system block, write the old contents of the block to +an undo file. This undo file can be used with e2undo(8) to restore the old +contents of the file system should something go wrong. If the empty string is +passed as the undo_file argument, the undo file will be written to a file named +mke2fs-\fIdevice\fR.e2undo in the directory specified via the +\fIE2FSPROGS_UNDO_DIR\fR environment variable or the \fIundo_dir\fR directive +in the configuration file. + +WARNING: The undo file cannot be used to recover from a power or system crash. +.SH ENVIRONMENT +.TP +.BI MKE2FS_SYNC +If set to non-zero integer value, its value is used to determine how often +.BR sync (2) +is called during inode table initialization. +.TP +.BI MKE2FS_CONFIG +Determines the location of the configuration file (see +.BR mke2fs.conf (5)). +.TP +.BI MKE2FS_FIRST_META_BG +If set to non-zero integer value, its value is used to determine first meta +block group. This is mostly for debugging purposes. +.TP +.BI MKE2FS_DEVICE_SECTSIZE +If set to non-zero integer value, its value is used to determine physical +sector size of the +.IR device . +.TP +.BI MKE2FS_SKIP_CHECK_MSG +If set, do not show the message of filesystem automatic check caused by +mount count or check interval. .SH AUTHOR This version of .B mke2fs @@ -363,10 +799,12 @@ extended file system does not support fragments yet. There may be other ones. Please, report them to the author. .SH AVAILABILITY .B mke2fs -is part of the e2fsprogs package and is available from +is part of the e2fsprogs package and is available from http://e2fsprogs.sourceforge.net. .SH SEE ALSO +.BR mke2fs.conf (5), .BR badblocks (8), .BR dumpe2fs (8), .BR e2fsck (8), -.BR tune2fs (8) +.BR tune2fs (8), +.BR ext4 (5)