xref: /freebsd/sbin/newfs/newfs.8 (revision 74bf4e164ba5851606a27d4feff27717452583e5)
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28.\"     @(#)newfs.8	8.6 (Berkeley) 5/3/95
29.\" $FreeBSD$
30.\"
31.Dd May 18, 2002
32.Dt NEWFS 8
33.Os
34.Sh NAME
35.Nm newfs
36.Nd construct a new UFS1/UFS2 file system
37.Sh SYNOPSIS
38.Nm
39.Op Fl NUl
40.Op Fl L Ar volname
41.Op Fl O Ar filesystem-type
42.Op Fl S Ar sector-size
43.Op Fl T Ar disktype
44.Op Fl a Ar maxcontig
45.Op Fl b Ar block-size
46.Op Fl c Ar blocks-per-cylinder-group
47.Op Fl d Ar max-extent-size
48.Op Fl e Ar maxbpg
49.Op Fl f Ar frag-size
50.Op Fl g Ar avgfilesize
51.Op Fl h Ar avgfpdir
52.Op Fl i Ar bytes
53.Op Fl m Ar free-space
54.Op Fl o Ar optimization
55.Op Fl s Ar size
56.Ar special
57.Sh DESCRIPTION
58The
59.Nm
60utility is used to initialize and clear file systems before first use.
61Before running
62.Nm
63the disk must be labeled using
64.Xr bsdlabel 8 .
65The
66.Nm
67utility builds a file system on the specified special file.
68(We often refer to the
69.Dq special file
70as the
71.Dq disk ,
72although the special file need not be a physical disk.
73In fact, it need not even be special.)
74Typically the defaults are reasonable, however
75.Nm
76has numerous options to allow the defaults to be selectively overridden.
77.Pp
78The following options define the general layout policies:
79.Bl -tag -width indent
80.It Fl L Ar volname
81Add a volume label to the new file system.
82.It Fl N
83Cause the file system parameters to be printed out
84without really creating the file system.
85.It Fl O Ar filesystem-type
86Use 1 to specify that a UFS1 format file system be built;
87use 2 to specify that a UFS2 format file system be built.
88The default format is UFS2.
89.It Fl T Ar disktype
90For backward compatibility.
91.It Fl U
92Enable soft updates on the new file system.
93.It Fl a Ar maxcontig
94Specify the maximum number of contiguous blocks that will be
95laid out before forcing a rotational delay.
96The default value is 16.
97See
98.Xr tunefs 8
99for more details on how to set this option.
100.It Fl b Ar block-size
101The block size of the file system, in bytes.
102It must be a power of 2.
103The
104default size is 16384 bytes, and the smallest allowable size is 4096 bytes.
105The optimal block:fragment ratio is 8:1.
106Other ratios are possible, but are not recommended,
107and may produce poor results.
108.It Fl c Ar blocks-per-cylinder-group
109The number of blocks per cylinder group in a file system.
110The default is to compute the maximum allowed by the other parameters.
111This value is
112dependent on a number of other parameters, in particular the block size
113and the number of bytes per inode.
114.It Fl d Ar max-extent-size
115The file system may choose to store large files using extents.
116This parameter specifies the largest extent size that may be used.
117It is presently limited to its default value which is 16 times
118the file system blocksize.
119.It Fl e Ar maxbpg
120Indicate the maximum number of blocks any single file can
121allocate out of a cylinder group before it is forced to begin
122allocating blocks from another cylinder group.
123The default is about one quarter of the total blocks in a cylinder group.
124See
125.Xr tunefs 8
126for more details on how to set this option.
127.It Fl f Ar frag-size
128The fragment size of the file system in bytes.
129It must be a power of two
130ranging in value between
131.Ar blocksize Ns /8
132and
133.Ar blocksize .
134The default is 2048 bytes.
135.It Fl g Ar avgfilesize
136The expected average file size for the file system.
137.It Fl h Ar avgfpdir
138The expected average number of files per directory on the file system.
139.It Fl i Ar bytes
140Specify the density of inodes in the file system.
141The default is to create an inode for every
142.Pq 4 * Ar frag-size
143bytes of data space.
144If fewer inodes are desired, a larger number should be used;
145to create more inodes a smaller number should be given.
146One inode is required for each distinct file, so this value effectively
147specifies the average file size on the file system.
148.It Fl l
149Enable multilabel MAC on the new file system.
150.It Fl m Ar free-space
151The percentage of space reserved from normal users; the minimum free
152space threshold.
153The default value used is
154defined by
155.Dv MINFREE
156from
157.In ufs/ffs/fs.h ,
158currently 8%.
159See
160.Xr tunefs 8
161for more details on how to set this option.
162.It Fl o Ar optimization
163.Cm ( space
164or
165.Cm time ) .
166The file system can either be instructed to try to minimize the time spent
167allocating blocks, or to try to minimize the space fragmentation on the disk.
168If the value of minfree (see above) is less than 8%,
169the default is to optimize for
170.Cm space ;
171if the value of minfree is greater than or equal to 8%,
172the default is to optimize for
173.Cm time .
174See
175.Xr tunefs 8
176for more details on how to set this option.
177.It Fl s Ar size
178The size of the file system in sectors.
179This value defaults to the size of the
180raw partition specified in
181.Ar special
182(in other words,
183.Nm
184will use the entire partition for the file system).
185.El
186.Pp
187The following options override the standard sizes for the disk geometry.
188Their default values are taken from the disk label.
189Changing these defaults is useful only when using
190.Nm
191to build a file system whose raw image will eventually be used on a
192different type of disk than the one on which it is initially created
193(for example on a write-once disk).
194Note that changing any of these values from their defaults will make
195it impossible for
196.Xr fsck 8
197to find the alternate superblocks if the standard superblock is lost.
198.Bl -tag -width indent
199.It Fl S Ar sector-size
200The size of a sector in bytes (almost never anything but 512).
201.El
202.Sh EXAMPLES
203.Dl newfs /dev/ad3s1a
204.Pp
205Creates a new ufs file system on
206.Pa ad3s1a .
207The
208.Nm
209utility will use a block size of 16384 bytes, a fragment size of 2048 bytes
210and the largest possible number of blocks per cylinders group.
211These values tend to produce better performance for most applications
212than the historical defaults
213(8192 byte block size and 1024 byte fragment size).
214This large fragment size may lead to much wasted space
215on file systems that contain many small files.
216.Sh SEE ALSO
217.Xr fdformat 1 ,
218.Xr disktab 5 ,
219.Xr fs 5 ,
220.Xr bsdlabel 8 ,
221.Xr camcontrol 8 ,
222.Xr dumpfs 8 ,
223.Xr fsck 8 ,
224.Xr mount 8 ,
225.Xr tunefs 8 ,
226.Xr vinum 8
227.Rs
228.%A M. McKusick
229.%A W. Joy
230.%A S. Leffler
231.%A R. Fabry
232.%T A Fast File System for UNIX
233.%J ACM Transactions on Computer Systems 2
234.%V 3
235.%P pp 181-197
236.%D August 1984
237.%O (reprinted in the BSD System Manager's Manual)
238.Re
239.Sh HISTORY
240The
241.Nm
242utility appeared in
243.Bx 4.2 .
244