NEWFS_EXT2FS(8)

NEWFS_EXT2FS(8) | System Manager's Manual | NEWFS_EXT2FS(8)

# NAME

newfs_ext2fs — construct a new ext2 file system

# SYNOPSIS

newfs_ext2fs | [-FINZ] [-b block-size] [-D inodesize] [-f frag-size] [-i bytes-per-inode] [-m free-space] [-n inodes] [-O filesystem-format] [-S sector-size] [-s size] [-V verbose] [-v volname] special

# DESCRIPTION

newfs_ext2fs is used to initialize and clear ext2 file systems before first use. Before running newfs_ext2fs the disk must be labeled using disklabel(8). newfs_ext2fs builds a file system on the specified special device basing its defaults on the information in the disk label. Typically the defaults are reasonable, however newfs_ext2fs has numerous options to allow the defaults to be selectively overridden.

Options with numeric arguments may contain an optional (case-insensitive) suffix:

b
  Bytes; causes no modification. (Default)
k
  Kilo; multiply the argument by 1024.
m
  Mega; multiply the argument by 1048576.
g
  Giga; multiply the argument by 1073741824.

The following options define the general layout policies.

-b block-size
  The block size of the file system, in bytes. It must be a power of two. The smallest allowable size is 1024 bytes. The default size depends upon the size of the file system:

  file system size
    block-size
  <= 512 MB
    1 KB
  > 512 MB
    4 KB
-D inodesize
  Set the inode size. Defaults to 128, and can also be set to 256 for compatibility with ext4.
-F
  Create a file system image in special. The file system size needs to be specified with “-s size”. No attempts to use or update the disk label will be made.
-f frag-size
  The fragment size of the file system in bytes. It must be the same with blocksize because the current ext2fs implementation doesn't support fragmentation.
-I
  Do not require that the file system type listed in the disk label is ‘`Linux Ext2`’.
-i bytes-per-inode
  This specifies the density of inodes in the file system. If fewer inodes are desired, a larger number should be used; to create more inodes a smaller number should be given.
-m free-space
  The percentage of space reserved from normal users; the minimum free space threshold. The default value used is 5%.
-N
  Causes the file system parameters to be printed out without really creating the file system.
-n inodes
  This specifies the number of inodes for the file system. If both -i and -n are specified then -n takes precedence. The default number of inodes is calculated from a number of blocks in the file system.
-O filesystem-format
  Select the filesystem-format.
  0
    ‘`GOOD_OLD_REV`’; this option is primarily used to build root file systems that can be understood by old or dumb firmwares for bootstrap. (default)
  1
    ‘`DYNAMIC_REV`’; various extended (and sometimes incompatible) features are enabled (though not all features are supported on NetBSD). Currently only the following features are supported:
    RESIZE
      Prepare some reserved structures which enable future file system resizing.
    FTYPE
      Store file types in directory entries to improve performance.
    SPARSESUPER
      Prepare superblock backups for the fsck_ext2fs(8) utility on not all but sparse block groups.
    LARGEFILE
      Enable files larger than 2G bytes.
-s size
  The size of the file system in sectors. An ‘s’ suffix will be interpreted as the number of sectors (the default). All other suffixes are interpreted as per other numeric arguments, except that the number is converted into sectors by dividing by the sector size (as specified by -S secsize) after suffix interpretation.

  If no -s size is specified then the filesystem size defaults to that of the partition, or, if -F is specified, the existing file.

  If size is negative the specified size is subtracted from the default size (reserving space at the end of the partition).

-V verbose
  This controls the amount of information written to stdout:
  0
    No output.
  1
    Overall size and cylinder group details.
  2
    A progress bar (dots ending at right hand margin).
  3
    The first few super-block backup sector numbers are displayed before the progress bar.
  4
    All the super-block backup sector numbers are displayed (no progress bar).
  The default is 3. If -N is specified newfs_ext2fs stops before outputting the progress bar.
-v volname
  This specifies a volume name for the file system.
-Z
  Pre-zeros the file system image created with -F. This is necessary if the image is to be used by vnd(4) (which doesn't support file systems with ‘holes’).

The following option overrides the standard sizes for the disk geometry. The default value is taken from the disk label. Changing this default is useful only when using newfs_ext2fs to build a file system whose raw image will eventually be used on a different type of disk than the one on which it is initially created (for example on a write-once disk). Note that changing this value from its default will make it impossible for fsck_ext2fs(8) to find the alternative superblocks if the standard superblock is lost.

-S sector-size
  The size of a sector in bytes (almost never anything but 512). Defaults to 512.

# NOTES

There is no option to specify the metadata byte order on the file system to be created because the native ext2 file system is always little endian even on big endian hosts.

The file system is created with ‘random’ inode generation numbers to improve NFS security.

The owner and group IDs of the root node and reserved blocks of the new file system are set to the effective UID and GID of the user initializing the file system.

For the newfs_ext2fs command to succeed, the disk label should first be updated such that the fstype field for the partition is set to ‘`Linux Ext2`’, unless -F or -I is used.

The partition size is found using fstat(2), not by inspecting the disk label. The block size and fragment size will be written back to the disk label only if the last character of special references the same partition as the minor device number.

# SEE ALSO

fstat(2), disklabel(5), disktab(5), fs(5), disklabel(8), diskpart(8), fsck_ext2fs(8), mount(8), mount_ext2fs(8), newfs(8)

Remy Card, Theodore Ts'o, and Stephen Tweedie, Design and Implementation of the Second Extended Filesystem, The Proceedings of the First Dutch International Symposium on Linux, http://e2fsprogs.sourceforge.net/ext2intro.html.

# HISTORY

The newfs_ext2fs command first appeared in NetBSD 5.0.

# AUTHORS

The newfs_ext2fs command was written by Izumi Tsutsui <tsutsui@NetBSD.org>.

# BUGS

The newfs_ext2fs command is still experimental and there are few sanity checks.

The newfs_ext2fs command doesn't have options to specify each REV1 file system feature independently.

The newfs_ext2fs command doesn't support the bad block list accounted by the bad blocks inode.

Many newer ext2 file system features (especially journaling) are not supported yet.

Some features in file systems created by the newfs_ext2fs command might not be recognized properly by the fsck_ext2fs(8) utility.

There is no native tool in the NetBSD distribution for resizing ext2 file systems yet.

March 1, 2009 | NetBSD 7.0