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
-
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 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 volname
-
This specifies a volume name for the file system.
- -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 specifed
newfs_ext2fs
stops before outputting the progress bar.
- -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 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 disklabel.
The block size and fragment size will be written back to the disklabel
only if the last character of
special
references the same partition as the minor device number.
that provide disk like block and character devices.
SEE ALSO
fstat(2),
disklabel(5),
disktab(5),
fs(5),
disklabel(8),
diskpart(8),
fsck_ext2fs(8),
mount(8),
mount_ext2fs(8),
newfs(8),
http://e2fsprogs.sourceforge.net/ext2intro.html
HISTORY
The
newfs_ext2fs
command first appeared in
NetBSD5.0.
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.