xref: /freebsd/sbin/newfs/newfs.8 (revision f0a75d274af375d15b97b830966b99a02b7db911)
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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 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 J
81Enable journaling on the new file system via gjournal.
82.It Fl L Ar volname
83Add a volume label to the new file system.
84.It Fl N
85Cause the file system parameters to be printed out
86without really creating the file system.
87.It Fl O Ar filesystem-type
88Use 1 to specify that a UFS1 format file system be built;
89use 2 to specify that a UFS2 format file system be built.
90The default format is UFS2.
91.It Fl T Ar disktype
92For backward compatibility.
93.It Fl U
94Enable soft updates on the new file system.
95.It Fl a Ar maxcontig
96Specify the maximum number of contiguous blocks that will be
97laid out before forcing a rotational delay.
98The default value is 16.
99See
100.Xr tunefs 8
101for more details on how to set this option.
102.It Fl b Ar block-size
103The block size of the file system, in bytes.
104It must be a power of 2.
105The
106default size is 16384 bytes, and the smallest allowable size is 4096 bytes.
107The optimal block:fragment ratio is 8:1.
108Other ratios are possible, but are not recommended,
109and may produce poor results.
110.It Fl c Ar blocks-per-cylinder-group
111The number of blocks per cylinder group in a file system.
112The default is to compute the maximum allowed by the other parameters.
113This value is
114dependent on a number of other parameters, in particular the block size
115and the number of bytes per inode.
116.It Fl d Ar max-extent-size
117The file system may choose to store large files using extents.
118This parameter specifies the largest extent size that may be used.
119It is presently limited to its default value which is 16 times
120the file system blocksize.
121.It Fl e Ar maxbpg
122Indicate the maximum number of blocks any single file can
123allocate out of a cylinder group before it is forced to begin
124allocating blocks from another cylinder group.
125The default is about one quarter of the total blocks in a cylinder group.
126See
127.Xr tunefs 8
128for more details on how to set this option.
129.It Fl f Ar frag-size
130The fragment size of the file system in bytes.
131It must be a power of two
132ranging in value between
133.Ar blocksize Ns /8
134and
135.Ar blocksize .
136The default is 2048 bytes.
137.It Fl g Ar avgfilesize
138The expected average file size for the file system.
139.It Fl h Ar avgfpdir
140The expected average number of files per directory on the file system.
141.It Fl i Ar bytes
142Specify the density of inodes in the file system.
143The default is to create an inode for every
144.Pq 4 * Ar frag-size
145bytes of data space.
146If fewer inodes are desired, a larger number should be used;
147to create more inodes a smaller number should be given.
148One inode is required for each distinct file, so this value effectively
149specifies the average file size on the file system.
150.It Fl l
151Enable multilabel MAC on the new file system.
152.It Fl m Ar free-space
153The percentage of space reserved from normal users; the minimum free
154space threshold.
155The default value used is
156defined by
157.Dv MINFREE
158from
159.In ufs/ffs/fs.h ,
160currently 8%.
161See
162.Xr tunefs 8
163for more details on how to set this option.
164.It Fl n
165Do not create a
166.Pa .snap
167directory on the new file system.
168The resulting file system will not support snapshot generation, so
169.Xr dump 8
170in live mode and background
171.Xr fsck 8
172will not function properly.
173The traditional
174.Xr fsck 8
175and offline
176.Xr dump 8
177will work on the file system.
178This option is intended primarily for memory or vnode-backed file systems that
179do not require
180.Xr dump 8
181or
182.Xr fsck 8
183support.
184.It Fl o Ar optimization
185.Cm ( space
186or
187.Cm time ) .
188The file system can either be instructed to try to minimize the time spent
189allocating blocks, or to try to minimize the space fragmentation on the disk.
190If the value of minfree (see above) is less than 8%,
191the default is to optimize for
192.Cm space ;
193if the value of minfree is greater than or equal to 8%,
194the default is to optimize for
195.Cm time .
196See
197.Xr tunefs 8
198for more details on how to set this option.
199.It Fl s Ar size
200The size of the file system in sectors.
201This value defaults to the size of the
202raw partition specified in
203.Ar special
204(in other words,
205.Nm
206will use the entire partition for the file system).
207.El
208.Pp
209The following options override the standard sizes for the disk geometry.
210Their default values are taken from the disk label.
211Changing these defaults is useful only when using
212.Nm
213to build a file system whose raw image will eventually be used on a
214different type of disk than the one on which it is initially created
215(for example on a write-once disk).
216Note that changing any of these values from their defaults will make
217it impossible for
218.Xr fsck 8
219to find the alternate superblocks if the standard superblock is lost.
220.Bl -tag -width indent
221.It Fl S Ar sector-size
222The size of a sector in bytes (almost never anything but 512).
223.El
224.Sh EXAMPLES
225.Dl newfs /dev/ad3s1a
226.Pp
227Creates a new ufs file system on
228.Pa ad3s1a .
229The
230.Nm
231utility will use a block size of 16384 bytes, a fragment size of 2048 bytes
232and the largest possible number of blocks per cylinders group.
233These values tend to produce better performance for most applications
234than the historical defaults
235(8192 byte block size and 1024 byte fragment size).
236This large fragment size may lead to much wasted space
237on file systems that contain many small files.
238.Sh SEE ALSO
239.Xr fdformat 1 ,
240.Xr disktab 5 ,
241.Xr fs 5 ,
242.Xr bsdlabel 8 ,
243.Xr camcontrol 8 ,
244.Xr dump 8 ,
245.Xr dumpfs 8 ,
246.Xr fsck 8 ,
247.Xr mount 8 ,
248.Xr tunefs 8 ,
249.Xr vinum 8
250.Rs
251.%A M. McKusick
252.%A W. Joy
253.%A S. Leffler
254.%A R. Fabry
255.%T A Fast File System for UNIX
256.%J ACM Transactions on Computer Systems 2
257.%V 3
258.%P pp 181-197
259.%D August 1984
260.%O (reprinted in the BSD System Manager's Manual)
261.Re
262.Sh HISTORY
263The
264.Nm
265utility appeared in
266.Bx 4.2 .
267