xref: /freebsd/sbin/newfs/newfs.8 (revision 35a04710d7286aa9538917fd7f8e417dbee95b82)
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28.\"     @(#)newfs.8	8.6 (Berkeley) 5/3/95
29.\" $FreeBSD$
30.\"
31.Dd January 21, 2005
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 JNUln
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 r Ar reserved
56.Op Fl s Ar size
57.Ar special
58.Sh DESCRIPTION
59The
60.Nm
61utility is used to initialize and clear file systems before first use.
62Before running
63.Nm
64the disk must be labeled using
65.Xr bsdlabel 8 .
66The
67.Nm
68utility builds a file system on the specified special file.
69(We often refer to the
70.Dq special file
71as the
72.Dq disk ,
73although the special file need not be a physical disk.
74In fact, it need not even be special.)
75Typically the defaults are reasonable, however
76.Nm
77has numerous options to allow the defaults to be selectively overridden.
78.Pp
79The following options define the general layout policies:
80.Bl -tag -width indent
81.It Fl J
82Enable journaling on the new file system via gjournal.
83.It Fl L Ar volname
84Add a volume label to the new file system.
85.It Fl N
86Cause the file system parameters to be printed out
87without really creating the file system.
88.It Fl O Ar filesystem-type
89Use 1 to specify that a UFS1 format file system be built;
90use 2 to specify that a UFS2 format file system be built.
91The default format is UFS2.
92.It Fl T Ar disktype
93For backward compatibility.
94.It Fl U
95Enable soft updates on the new file system.
96.It Fl a Ar maxcontig
97Specify the maximum number of contiguous blocks that will be
98laid out before forcing a rotational delay.
99The default value is 16.
100See
101.Xr tunefs 8
102for more details on how to set this option.
103.It Fl b Ar block-size
104The block size of the file system, in bytes.
105It must be a power of 2.
106The
107default size is 16384 bytes, and the smallest allowable size is 4096 bytes.
108The optimal block:fragment ratio is 8:1.
109Other ratios are possible, but are not recommended,
110and may produce poor results.
111.It Fl c Ar blocks-per-cylinder-group
112The number of blocks per cylinder group in a file system.
113The default is to compute the maximum allowed by the other parameters.
114This value is
115dependent on a number of other parameters, in particular the block size
116and the number of bytes per inode.
117.It Fl d Ar max-extent-size
118The file system may choose to store large files using extents.
119This parameter specifies the largest extent size that may be used.
120It is presently limited to its default value which is 16 times
121the file system blocksize.
122.It Fl e Ar maxbpg
123Indicate the maximum number of blocks any single file can
124allocate out of a cylinder group before it is forced to begin
125allocating blocks from another cylinder group.
126The default is about one quarter of the total blocks in a cylinder group.
127See
128.Xr tunefs 8
129for more details on how to set this option.
130.It Fl f Ar frag-size
131The fragment size of the file system in bytes.
132It must be a power of two
133ranging in value between
134.Ar blocksize Ns /8
135and
136.Ar blocksize .
137The default is 2048 bytes.
138.It Fl g Ar avgfilesize
139The expected average file size for the file system.
140.It Fl h Ar avgfpdir
141The expected average number of files per directory on the file system.
142.It Fl i Ar bytes
143Specify the density of inodes in the file system.
144The default is to create an inode for every
145.Pq 4 * Ar frag-size
146bytes of data space.
147If fewer inodes are desired, a larger number should be used;
148to create more inodes a smaller number should be given.
149One inode is required for each distinct file, so this value effectively
150specifies the average file size on the file system.
151.It Fl l
152Enable multilabel MAC on the new file system.
153.It Fl m Ar free-space
154The percentage of space reserved from normal users; the minimum free
155space threshold.
156The default value used is
157defined by
158.Dv MINFREE
159from
160.In ufs/ffs/fs.h ,
161currently 8%.
162See
163.Xr tunefs 8
164for more details on how to set this option.
165.It Fl n
166Do not create a
167.Pa .snap
168directory on the new file system.
169The resulting file system will not support snapshot generation, so
170.Xr dump 8
171in live mode and background
172.Xr fsck 8
173will not function properly.
174The traditional
175.Xr fsck 8
176and offline
177.Xr dump 8
178will work on the file system.
179This option is intended primarily for memory or vnode-backed file systems that
180do not require
181.Xr dump 8
182or
183.Xr fsck 8
184support.
185.It Fl o Ar optimization
186.Cm ( space
187or
188.Cm time ) .
189The file system can either be instructed to try to minimize the time spent
190allocating blocks, or to try to minimize the space fragmentation on the disk.
191If the value of minfree (see above) is less than 8%,
192the default is to optimize for
193.Cm space ;
194if the value of minfree is greater than or equal to 8%,
195the default is to optimize for
196.Cm time .
197See
198.Xr tunefs 8
199for more details on how to set this option.
200.It Fl r Ar reserved
201The size, in sectors, of reserved space
202at the end of the partition specified in
203.Ar special .
204This space will not be occupied by the file system;
205it can be used by other consumers such as
206.Xr geom 4 .
207Defaults to 0.
208.It Fl s Ar size
209The size of the file system in sectors.
210This value defaults to the size of the
211raw partition specified in
212.Ar special
213less the
214.Ar reserved
215space at its end (see
216.Fl r ) .
217A
218.Ar size
219of 0 can also be used to choose the default value.
220A valid
221.Ar size
222value cannot be larger than the default one,
223which means that the file system cannot extend into the reserved space.
224.El
225.Pp
226The following options override the standard sizes for the disk geometry.
227Their default values are taken from the disk label.
228Changing these defaults is useful only when using
229.Nm
230to build a file system whose raw image will eventually be used on a
231different type of disk than the one on which it is initially created
232(for example on a write-once disk).
233Note that changing any of these values from their defaults will make
234it impossible for
235.Xr fsck 8
236to find the alternate superblocks if the standard superblock is lost.
237.Bl -tag -width indent
238.It Fl S Ar sector-size
239The size of a sector in bytes (almost never anything but 512).
240.El
241.Sh EXAMPLES
242.Dl newfs /dev/ad3s1a
243.Pp
244Creates a new ufs file system on
245.Pa ad3s1a .
246The
247.Nm
248utility will use a block size of 16384 bytes, a fragment size of 2048 bytes
249and the largest possible number of blocks per cylinders group.
250These values tend to produce better performance for most applications
251than the historical defaults
252(8192 byte block size and 1024 byte fragment size).
253This large fragment size may lead to much wasted space
254on file systems that contain many small files.
255.Sh SEE ALSO
256.Xr fdformat 1 ,
257.Xr geom 4 ,
258.Xr disktab 5 ,
259.Xr fs 5 ,
260.Xr bsdlabel 8 ,
261.Xr camcontrol 8 ,
262.Xr dump 8 ,
263.Xr dumpfs 8 ,
264.Xr fsck 8 ,
265.Xr mount 8 ,
266.Xr tunefs 8 ,
267.Xr vinum 8
268.Rs
269.%A M. McKusick
270.%A W. Joy
271.%A S. Leffler
272.%A R. Fabry
273.%T A Fast File System for UNIX
274.%J ACM Transactions on Computer Systems 2
275.%V 3
276.%P pp 181-197
277.%D August 1984
278.%O (reprinted in the BSD System Manager's Manual)
279.Re
280.Sh HISTORY
281The
282.Nm
283utility appeared in
284.Bx 4.2 .
285