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.