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@(#)newfs.8 8.6 (Berkeley) 5/3/95
$FreeBSD: head/sbin/newfs/newfs.8 101800 2002-08-13 13:13:20Z ru $
.Dd May 18, 2002 .Dt NEWFS 8 .Os .Sh NAME .Nm newfs , .Nd construct a new filesystem .Sh SYNOPSIS .Nm .Op Fl NU .Op Fl O Ar filesystem-type .Op Fl S Ar sector-size .Op Fl T Ar disktype .Op Fl a Ar maxcontig .Op Fl b Ar block-size .Op Fl c Ar blocks-per-cylinder-group .Op Fl d Ar max-extent-size .Op Fl e Ar maxbpg .Op Fl f Ar frag-size .Op Fl g Ar avgfilesize .Op Fl h Ar avgfpdir .Op Fl i Ar bytes .Op Fl m Ar free-space .Op Fl o Ar optimization .Op Fl s Ar size .Ar special .Sh DESCRIPTION The .Nm utility is used to initialize and clear filesystems before first use. Before running .Nm the disk must be labeled using .Xr disklabel 8 . The .Nm utility builds a filesystem on the specified special file. (We often refer to the .Dq special file as the .Dq disk , although the special file need not be a physical disk. In fact, it need not even be special.) Typically the defaults are reasonable, however .Nm has numerous options to allow the defaults to be selectively overridden.
p The following options define the general layout policies: l -tag -width indent t Fl T Ar disktype For backward compatibility. t Fl N Cause the filesystem parameters to be printed out without really creating the filesystem. t Fl O Ar filesystem-type Use 1 to specify that a UFS1 format filesystem be built; use 2 to specify that a UFS2 format filesystem be built. The default is UFS1 format, but will eventually be changed to UFS2. t Fl U Enables soft updates on the new filesystem. t Fl a Ar maxcontig Specify the maximum number of contiguous blocks that will be laid out before forcing a rotational delay. The default value is 16. See .Xr tunefs 8 for more details on how to set this option. t Fl b Ar block-size The block size of the filesystem, in bytes. It must be a power of 2. The default size is 16384 bytes, and the smallest allowable size is 4096 bytes. The optimal block:fragment ratio is 8:1. Other ratios are possible, but are not recommended, and may produce poor results. t Fl c Ar blocks-per-cylinder-group The number of blocks per cylinder group in a filesystem. The default is to compute the maximum allowed by the other parameters. This value is dependent on a number of other parameters, in particular the block size and the number of bytes per inode. t Fl d Ar max-extent-size The filesystem may choose to store large files using extents. This parameter specifies the largest extent size that may be used. It is presently limited to its default value which is 16 times the filesystem blocksize. t Fl e Ar maxbpg Indicate the maximum number of blocks any single file can allocate out of a cylinder group before it is forced to begin allocating blocks from another cylinder group. The default is about one quarter of the total blocks in a cylinder group. See .Xr tunefs 8 for more details on how to set this option. t Fl f Ar frag-size The fragment size of the filesystem in bytes. It must be a power of two ranging in value between .Ar blocksize Ns /8 and .Ar blocksize . The default is 2048 bytes. t Fl g Ar avgfilesize The expected average file size for the filesystem. t Fl h Ar avgfpdir The expected average number of files per directory on the filesystem. t Fl i Ar bytes Specify the density of inodes in the filesystem. The default is to create an inode for every
q 4 * Ar frag-size bytes of data space. If fewer inodes are desired, a larger number should be used; to create more inodes a smaller number should be given. One inode is required for each distinct file, so this value effectively specifies the average file size on the filesystem. t Fl m Ar free-space The percentage of space reserved from normal users; the minimum free space threshold. The default value used is defined by .Dv MINFREE from .Aq Pa ufs/ffs/fs.h , currently 8%. See .Xr tunefs 8 for more details on how to set this option. t Fl o Ar optimization .Cm ( space or .Cm time ) . The filesystem can either be instructed to try to minimize the time spent allocating blocks, or to try to minimize the space fragmentation on the disk. If the value of minfree (see above) is less than 8%, the default is to optimize for .Cm space ; if the value of minfree is greater than or equal to 8%, the default is to optimize for .Cm time . See .Xr tunefs 8 for more details on how to set this option. t Fl s Ar size The size of the filesystem in sectors. This value defaults to the size of the raw partition specified in .Ar special (in other words, .Nm will use the entire partition for the filesystem). .El
p The following options override the standard sizes for the disk geometry. Their default values are taken from the disk label. Changing these defaults is useful only when using .Nm to build a filesystem 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 any of these values from their defaults will make it impossible for .Xr fsck 8 to find the alternate superblocks if the standard superblock is lost. l -tag -width indent t Fl S Ar sector-size The size of a sector in bytes (almost never anything but 512). .El .Sh EXAMPLES .Dl newfs /dev/ad3s1a
p Creates a new ufs filesystem on
a ad3s1a . The .Nm utility will use a block size of 16384 bytes, a fragment size of 2048 bytes and the largest possible number of blocks per cylinders group. These values tend to produce better performance for most applications than the historical defaults (8192 byte block size and 1024 byte fragment size). This large fragment size may lead to much wasted space on filesystems that contain many small files. .Sh SEE ALSO .Xr fdformat 1 , .Xr disktab 5 , .Xr fs 5 , .Xr camcontrol 8 , .Xr disklabel 8 , .Xr diskpart 8 , .Xr dumpfs 8 , .Xr fsck 8 , .Xr mount 8 , .Xr tunefs 8 , .Xr vinum 8 .Rs .%A M. McKusick .%A W. Joy .%A S. Leffler .%A R. Fabry .%T A Fast File System for UNIX .%J ACM Transactions on Computer Systems 2 .%V 3 .%P pp 181-197 .%D August 1984 .%O (reprinted in the BSD System Manager's Manual) .Re .Sh HISTORY The .Nm utility appeared in x 4.2 .