xref: /freebsd/sbin/newfs/newfs.8 (revision eb69d1f144a6fcc765d1b9d44a5ae8082353e70b)
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28.\"     @(#)newfs.8	8.6 (Berkeley) 5/3/95
29.\" $FreeBSD$
30.\"
31.Dd July 7, 2017
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 EJNUjlnt
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 k Ar held-for-metadata-blocks
54.Op Fl m Ar free-space
55.Op Fl o Ar optimization
56.Op Fl p Ar partition
57.Op Fl r Ar reserved
58.Op Fl s Ar size
59.Ar special
60.Sh DESCRIPTION
61The
62.Nm
63utility is used to initialize and clear file systems before first use.
64The
65.Nm
66utility builds a file system on the specified special file.
67(We often refer to the
68.Dq special file
69as the
70.Dq disk ,
71although the special file need not be a physical disk.
72In fact, it need not even be special.)
73Typically the defaults are reasonable, however
74.Nm
75has numerous options to allow the defaults to be selectively overridden.
76.Pp
77The following options define the general layout policies:
78.Bl -tag -width indent
79.It Fl E
80Erase the content of the disk before making the filesystem.
81The reserved area in front of the superblock (for bootcode) will not be erased.
82Erasing is only relevant to flash-memory or thinly provisioned devices.
83Erasing may take a long time.
84If the device does not support BIO_DELETE, the command will fail.
85.It Fl J
86Enable journaling on the new file system via gjournal.
87See
88.Xr gjournal 8
89for details.
90.It Fl L Ar volname
91Add a volume label to the new file system.
92.It Fl N
93Cause the file system parameters to be printed out
94without really creating the file system.
95.It Fl O Ar filesystem-type
96Use 1 to specify that a UFS1 format file system be built;
97use 2 to specify that a UFS2 format file system be built.
98The default format is UFS2.
99.It Fl T Ar disktype
100For backward compatibility.
101.It Fl U
102Enable soft updates on the new file system.
103.It Fl a Ar maxcontig
104Specify the maximum number of contiguous blocks that will be
105laid out before forcing a rotational delay.
106The default value is 16.
107See
108.Xr tunefs 8
109for more details on how to set this option.
110.It Fl b Ar block-size
111The block size of the file system, in bytes.
112It must be a power of 2.
113The
114default size is 32768 bytes, and the smallest allowable size is 4096 bytes.
115The optimal block:fragment ratio is 8:1.
116Other ratios are possible, but are not recommended,
117and may produce poor results.
118.It Fl c Ar blocks-per-cylinder-group
119The number of blocks per cylinder group in a file system.
120The default is to compute the maximum allowed by the other parameters.
121This value is
122dependent on a number of other parameters, in particular the block size
123and the number of bytes per inode.
124.It Fl d Ar max-extent-size
125The file system may choose to store large files using extents.
126This parameter specifies the largest extent size that may be used.
127The default value is the file system blocksize.
128It is presently limited to a maximum value of 16 times the
129file system blocksize and a minimum value of the file system blocksize.
130.It Fl e Ar maxbpg
131Indicate the maximum number of blocks any single file can
132allocate out of a cylinder group before it is forced to begin
133allocating blocks from another cylinder group.
134The default is about one quarter of the total blocks in a cylinder group.
135See
136.Xr tunefs 8
137for more details on how to set this option.
138.It Fl f Ar frag-size
139The fragment size of the file system in bytes.
140It must be a power of two
141ranging in value between
142.Ar blocksize Ns /8
143and
144.Ar blocksize .
145The default is 4096 bytes.
146.It Fl g Ar avgfilesize
147The expected average file size for the file system.
148.It Fl h Ar avgfpdir
149The expected average number of files per directory on the file system.
150.It Fl i Ar bytes
151Specify the density of inodes in the file system.
152The default is to create an inode for every
153.Pq 2 * Ar frag-size
154bytes of data space.
155If fewer inodes are desired, a larger number should be used;
156to create more inodes a smaller number should be given.
157One inode is required for each distinct file, so this value effectively
158specifies the average file size on the file system.
159.It Fl j
160Enable soft updates journaling on the new file system.
161This flag is implemented by running the
162.Xr tunefs 8
163utility found in the user's
164.Dv $PATH .
165.It Fl k Ar held-for-metadata-blocks
166Set the amount of space to be held for metadata blocks in each cylinder group.
167When set, the file system preference routines will try to save
168the specified amount of space immediately following the inode blocks
169in each cylinder group for use by metadata blocks.
170Clustering the metadata blocks speeds up random file access
171and decreases the running time of
172.Xr fsck 8 .
173By default
174.Nm
175sets it to half of the space reserved to minfree.
176.It Fl l
177Enable multilabel MAC on the new file system.
178.It Fl m Ar free-space
179The percentage of space reserved from normal users; the minimum free
180space threshold.
181The default value used is
182defined by
183.Dv MINFREE
184from
185.In ufs/ffs/fs.h ,
186currently 8%.
187See
188.Xr tunefs 8
189for more details on how to set this option.
190.It Fl n
191Do not create a
192.Pa .snap
193directory on the new file system.
194The resulting file system will not support snapshot generation, so
195.Xr dump 8
196in live mode and background
197.Xr fsck 8
198will not function properly.
199The traditional
200.Xr fsck 8
201and offline
202.Xr dump 8
203will work on the file system.
204This option is intended primarily for memory or vnode-backed file systems that
205do not require
206.Xr dump 8
207or
208.Xr fsck 8
209support.
210.It Fl o Ar optimization
211.Cm ( space
212or
213.Cm time ) .
214The file system can either be instructed to try to minimize the time spent
215allocating blocks, or to try to minimize the space fragmentation on the disk.
216If the value of minfree (see above) is less than 8%,
217the default is to optimize for
218.Cm space ;
219if the value of minfree is greater than or equal to 8%,
220the default is to optimize for
221.Cm time .
222See
223.Xr tunefs 8
224for more details on how to set this option.
225.It Fl p Ar partition
226The partition name (a..h) you want to use in case the underlying image
227is a file, so you do not have access to individual partitions through the
228filesystem.
229Can also be used with a device, e.g.,
230.Nm
231.Fl p Ar f
232.Ar /dev/da1s3
233is equivalent to
234.Nm
235.Ar /dev/da1s3f .
236.It Fl r Ar reserved
237The size, in sectors, of reserved space
238at the end of the partition specified in
239.Ar special .
240This space will not be occupied by the file system;
241it can be used by other consumers such as
242.Xr geom 4 .
243Defaults to 0.
244.It Fl s Ar size
245The size of the file system in sectors.
246This value defaults to the size of the
247raw partition specified in
248.Ar special
249less the
250.Ar reserved
251space at its end (see
252.Fl r ) .
253A
254.Ar size
255of 0 can also be used to choose the default value.
256A valid
257.Ar size
258value cannot be larger than the default one,
259which means that the file system cannot extend into the reserved space.
260.It Fl t
261Turn on the TRIM enable flag.
262If enabled, and if the underlying device supports the BIO_DELETE
263command, the file system will send a delete request to the underlying
264device for each freed block.
265The trim enable flag is typically set for flash-memory devices to
266reduce write amplification which reduces wear on write-limited
267flash-memory and often improves long-term performance.
268Thinly provisioned storage also benefits by returning unused blocks to
269the global pool.
270.El
271.Pp
272The following options override the standard sizes for the disk geometry.
273Their default values are taken from the disk label.
274Changing these defaults is useful only when using
275.Nm
276to build a file system whose raw image will eventually be used on a
277different type of disk than the one on which it is initially created
278(for example on a write-once disk).
279Note that changing any of these values from their defaults will make
280it impossible for
281.Xr fsck 8
282to find the alternate superblocks if the standard superblock is lost.
283.Bl -tag -width indent
284.It Fl S Ar sector-size
285The size of a sector in bytes (almost never anything but 512).
286.El
287.Sh EXAMPLES
288.Dl newfs /dev/ada3s1a
289.Pp
290Creates a new ufs file system on
291.Pa ada3s1a .
292The
293.Nm
294utility will use a block size of 32768 bytes, a fragment size of 4096 bytes
295and the largest possible number of blocks per cylinders group.
296These values tend to produce better performance for most applications
297than the historical defaults
298(8192 byte block size and 1024 byte fragment size).
299This large fragment size may lead to much wasted space
300on file systems that contain many small files.
301.Sh SEE ALSO
302.Xr fdformat 1 ,
303.Xr geom 4 ,
304.Xr disktab 5 ,
305.Xr fs 5 ,
306.Xr camcontrol 8 ,
307.Xr dump 8 ,
308.Xr dumpfs 8 ,
309.Xr fsck 8 ,
310.Xr gpart 8 ,
311.Xr gjournal 8 ,
312.Xr growfs 8 ,
313.Xr gvinum 8 ,
314.Xr makefs 8 ,
315.Xr mount 8 ,
316.Xr tunefs 8
317.Rs
318.%A M. McKusick
319.%A W. Joy
320.%A S. Leffler
321.%A R. Fabry
322.%T A Fast File System for UNIX
323.%J ACM Transactions on Computer Systems 2
324.%V 3
325.%P pp 181-197
326.%D August 1984
327.%O (reprinted in the BSD System Manager's Manual)
328.Re
329.Sh HISTORY
330The
331.Nm
332utility appeared in
333.Bx 4.2 .
334