Device layer rollup commit.
[dragonfly.git] / sbin / newfs / newfs.8
CommitLineData
984263bc
MD
1.\" Copyright (c) 1983, 1987, 1991, 1993, 1994
2.\" The Regents of the University of California. All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\" notice, this list of conditions and the following disclaimer in the
11.\" documentation and/or other materials provided with the distribution.
12.\" 3. All advertising materials mentioning features or use of this software
13.\" must display the following acknowledgement:
14.\" This product includes software developed by the University of
15.\" California, Berkeley and its contributors.
16.\" 4. Neither the name of the University nor the names of its contributors
17.\" may be used to endorse or promote products derived from this software
18.\" without specific prior written permission.
19.\"
20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30.\" SUCH DAMAGE.
31.\"
32.\" @(#)newfs.8 8.6 (Berkeley) 5/3/95
33.\" $FreeBSD: src/sbin/newfs/newfs.8,v 1.26.2.15 2003/05/13 12:16:08 joerg Exp $
e4c9c0c8 34.\" $DragonFly: src/sbin/newfs/newfs.8,v 1.4 2004/05/19 22:52:34 dillon Exp $
984263bc
MD
35.\"
36.Dd May 13, 2003
37.Dt NEWFS 8
38.Os
39.Sh NAME
40.Nm newfs ,
41.Nm mount_mfs
42.Nd construct a new file system
43.Sh SYNOPSIS
44.Nm
65087744 45.Op Fl NCOU
984263bc
MD
46.Op Fl S Ar sector-size
47.Op Fl T Ar disktype
48.Op Fl a Ar maxcontig
49.Op Fl b Ar block-size
50.Op Fl c Ar cylinders
51.Op Fl d Ar rotdelay
52.Op Fl e Ar maxbpg
53.Op Fl f Ar frag-size
54.Op Fl g Ar avgfilesize
55.Op Fl h Ar avfpdir
56.Op Fl i Ar bytes
57.Op Fl k Ar skew
58.Op Fl l Ar interleave
59.Op Fl m Ar free space
60.Op Fl n Ar rotational positions
61.Op Fl o Ar optimization
62.Op Fl p Ar sectors
63.Op Fl r Ar revolutions
64.Op Fl s Ar size
65.Op Fl t Ar tracks
66.Op Fl u Ar sectors
67.Op Fl v
68.Op Fl x Ar sectors
69.Ar special
70.Nm mount_mfs
71.Op Fl NU
72.Op Fl F Ar file
73.Op Fl T Ar disktype
74.Op Fl a Ar maxcontig
75.Op Fl b Ar block-size
76.Op Fl c Ar cylinders
77.Op Fl d Ar rotdelay
78.Op Fl e Ar maxbpg
79.Op Fl f Ar frag-size
80.Op Fl i Ar bytes
81.Op Fl m Ar free space
82.Op Fl n Ar rotational positions
83.Op Fl o Ar options
84.Op Fl s Ar size
85.Op Fl v
86.Ar special node
87.Sh DESCRIPTION
88.Nm Newfs
89is used to initialize and clear filesystems before first use.
90Before running
91.Nm
92or
93.Nm mount_mfs ,
94the disk must be labeled using
95.Xr disklabel 8 .
96.Nm Newfs
97builds a file system on the specified special file.
98(We often refer to the
99.Dq special file
100as the
101.Dq disk ,
102although the special file need not be a physical disk.
103In fact, it need not even be special.)
104Typically the defaults are reasonable, however
105.Nm
106has numerous options to allow the defaults to be selectively overridden.
107.Pp
108.Nm Mount_mfs
109is used to build a file system in virtual memory and then mount it
110on a specified node.
111.Nm Mount_mfs
112exits and the contents of the file system are lost
113when the file system is unmounted.
114If
115.Nm mount_mfs
116is sent a signal while running,
117for example during system shutdown,
118it will attempt to unmount its
119corresponding file system.
120The parameters to
121.Nm mount_mfs
122are the same as those to
123.Nm .
124If the
125.Fl T
126flag is specified (see below), the special file is unused.
127Otherwise, it is only used to read the disk label which provides
128a set of configuration parameters for the memory based file system.
129The special file is typically that of the primary swap area,
130since that is where the file system will be backed up when
131free memory gets low and the memory supporting
132the file system has to be paged.
133.Pp
e4c9c0c8
MD
134.Nm mount_mfs
135creates the raw character device
136.Pa /dev/mfs<PID>
137to represent the backing store while the mount is active. This device may
138be read but not written and allows swap-based MFS filesystems to be dumped
139if desired.
140.Pp
984263bc
MD
141The following options define the general layout policies:
142.Bl -tag -width indent
143.It Fl T Ar disktype
144For backward compatibility and for
145.Nm mount_mfs .
146.It Fl F Ar file
147.Nm Mount_mfs
148will use this file for the image of the filesystem. When
149.Nm mount_mfs
150exits, this file will be left behind.
65087744
MD
151.It Fl C
152Tell
153.Nm Mount_mfs
154to copy the underlying filesystem into the MFS mount being created
155over it.
984263bc
MD
156.It Fl N
157Cause the file system parameters to be printed out
158without really creating the file system.
159.It Fl O
160Create a
161.Bx 4.3
162format filesystem.
163This options is primarily used to build root filesystems
164that can be understood by older boot ROMs.
165.It Fl T
166Use information for the specified disk from
167.Pa /etc/disktab
168instead of trying to get the information from a disklabel.
169.It Fl U
170Enables soft updates on the new filesystem.
171.It Fl a Ar maxcontig
172Specify the maximum number of contiguous blocks that will be
173laid out before forcing a rotational delay (see the
174.Fl d
175option).
176The default value is 1.
177See
178.Xr tunefs 8
179for more details on how to set this option.
180.It Fl b Ar block-size
181The block size of the file system, in bytes. It must be a power of 2. The
182default size is 16384 bytes, and the smallest allowable size is 4096 bytes.
183The optimal block:fragment ratio is 8:1.
184Other ratios are possible, but are not recommended,
185and may produce unpredictable results.
186.It Fl c Ar #cylinders/group
187The number of cylinders per cylinder group in a file system. The default
188is to compute the maximum allowed by the other parameters. This value is
189dependent on a number of other parameters, in particular the block size
190and the number of bytes per inode.
191.It Fl d Ar rotdelay
192This parameter once specified the minimum time in milliseconds required to
193initiate another disk transfer on the same cylinder. It was used in determining
194the rotationally optimal layout for disk blocks within a file. Modern disks
195with read/write-behind achieve higher performance with this feature disabled, so
196this value should be left at the default value of 0 milliseconds. See
197.Xr tunefs 8
198for more details on how to set this option.
199.It Fl e Ar maxbpg
200Indicate the maximum number of blocks any single file can
201allocate out of a cylinder group before it is forced to begin
202allocating blocks from another cylinder group.
203The default is about one quarter of the total blocks in a cylinder group.
204See
205.Xr tunefs 8
206for more details on how to set this option.
207.It Fl f Ar frag-size
208The fragment size of the file system in bytes. It must be a power of two
209ranging in value between
210.Ar blocksize Ns /8
211and
212.Ar blocksize .
213The default is 2048 bytes.
214.It Fl g Ar avgfilesize
215The expected average file size for the file system.
216.It Fl h Ar avgfpdir
217The expected average number of files per directory on the file system.
218.It Fl i Ar number of bytes per inode
219Specify the density of inodes in the file system.
220The default is to create an inode for every
221.Pq 4 * Ar frag-size
222bytes of data space.
223If fewer inodes are desired, a larger number should be used;
224to create more inodes a smaller number should be given.
225One inode is required for each distinct file, so this value effectively
226specifies the average file size on the file system.
227.It Fl m Ar free space \&%
228The percentage of space reserved from normal users; the minimum free
229space threshold.
230The default value used is
231defined by
232.Dv MINFREE
233from
234.Aq Pa ufs/ffs/fs.h ,
235currently 8%.
236See
237.Xr tunefs 8
238for more details on how to set this option.
239.It Fl n Ar number of distinguished rotational positions
240UFS has the ability to keep track of the availability of blocks at different
241rotational positions, so that it could lay out the data to be picked up with
242minimum rotational latency. This parameter specifies the default number of
243rotational positions to distinguish.
244.Pp
245Nowadays this value should be set to 1 (which essentially disables the
246rotational position table) because modern drives with read-ahead and
247write-behind do better without the rotational position table.
248.It Fl o Ar optimization\ preference
249.Pq Ar space No or Ar time .
250The file system can either be instructed to try to minimize the time spent
251allocating blocks, or to try to minimize the space fragmentation on the disk.
252If the value of minfree (see above) is less than 8%,
253the default is to optimize for
254.Ar space ;
255if the value of minfree is greater than or equal to 8%,
256the default is to optimize for
257.Ar time .
258See
259.Xr tunefs 8
260for more details on how to set this option.
261.It Fl s Ar size
262The size of the file system in sectors. This value defaults to the size of the
263raw partition specified in
264.Ar special
265(in other words,
266.Nm
267will use the entire partition for the file system).
268.It Fl v
269Specify that the disk does not contain any partitions, and that
270.Nm
271should build a file system on the whole disk.
272This option is useful for synthetic disks such as
273.Nm vinum .
274.El
275.Pp
276The following options override the standard sizes for the disk geometry.
277Their default values are taken from the disk label.
278Changing these defaults is useful only when using
279.Nm
280to build a file system whose raw image will eventually be used on a
281different type of disk than the one on which it is initially created
282(for example on a write-once disk).
283Note that changing any of these values from their defaults will make
284it impossible for
285.Xr fsck 8
286to find the alternate superblocks if the standard superblock is lost.
287.Bl -tag -width indent
288.It Fl S Ar sector-size
289The size of a sector in bytes (almost never anything but 512).
290.It Fl k Ar sector \&0 skew , per track
291Used to describe perturbations in the media format to compensate for
292a slow controller.
293Track skew is the offset of sector 0 on track N relative to sector 0
294on track N-1 on the same cylinder.
295This option is of historical importance only; modern controllers are always fast
296enough to handle operations back-to-back.
297.It Fl l Ar hardware sector interleave
298Used to describe perturbations in the media format to compensate for
299a slow controller.
300Interleave is physical sector interleave on each track,
301specified as the denominator of the ratio:
302.Dl sectors read/sectors passed over
303Thus an interleave of 1/1 implies contiguous layout, while 1/2 implies
304logical sector 0 is separated by one sector from logical sector 1.
305This option is of historical importance only; the physical sector layout of
306modern disks is not visible from outside.
307.It Fl p Ar spare sectors per track
308Spare sectors (bad sector replacements) are physical sectors that occupy
309space at the end of each track.
310They are not counted as part of the sectors/track
311.Pq Fl u
312since they are not available to the file system for data allocation.
313This option is of historical importance only. Modern disks perform their own
314bad sector allocation.
315.It Fl r Ar revolutions/minute
316The speed of the disk in revolutions per minute. This value is no longer of
317interest, since all the parameters which depend on it are usually disabled.
318.It Fl t Ar #tracks/cylinder
319The number of tracks/cylinder available for data allocation by the file
320system.
321The default is 1.
322If zero is specified, the value from the disklabel will be used.
323.It Fl u Ar sectors/track
324The number of sectors per track available for data allocation by the file
325system.
326The default is 4096.
327If zero is specified, the value from the disklabel will be used.
328This does not include sectors reserved at the end of each track for bad
329block replacement (see the
330.Fl p
331option).
332.It Fl x Ar spare sectors per cylinder
333Spare sectors (bad sector replacements) are physical sectors that occupy
334space at the end of the last track in the cylinder.
335They are deducted from the sectors/track
336.Pq Fl u
337of the last track of each cylinder since they are not available to the file
338system for data allocation.
339This option is of historical importance only. Modern disks perform their own
340bad sector allocation.
341.El
342.Pp
343The options to the
344.Nm mount_mfs
345command are as described for the
346.Nm
347command, except for the
348.Fl o
349option.
350.Pp
351That option is as follows:
352.Bl -tag -width indent
353.It Fl o
354Options are specified with a
355.Fl o
356flag followed by a comma separated string of options.
357See the
358.Xr mount 8
359man page for possible options and their meanings.
360.El
361.Sh EXAMPLES
362.Dl newfs /dev/ad3s1a
363.Pp
364Creates a new ufs file system on
365.Pa ad3s1a .
366.Nm
367will use a block size of 16384 bytes, a fragment size of 2048 bytes
368and the largest possible number of cylinders per group.
369These values tend to produce better performance for most applications
370than the historical defaults
371(8192 byte block size and 1024 byte fragment size).
372This large fragment size
373may lead to large amounts of wasted space
374on filesystems that contain a large number of small files.
375.Pp
376.Dl mount_mfs -s 131072 -o nosuid,nodev,nosymfollow /dev/da0s1b /tmp
377.Pp
378Mount a 64 MB large memory file system on
379.Pa /tmp ,
380with
381.Xr mount 8
382options
383.Ar nosuid ,
384.Ar nodev ,
385and
386.Ar nosymfollow .
387.Sh SEE ALSO
388.Xr fdformat 1 ,
389.Xr disktab 5 ,
390.Xr fs 5 ,
391.Xr camcontrol 8 ,
392.Xr disklabel 8 ,
393.Xr diskpart 8 ,
394.Xr dumpfs 8 ,
395.Xr fsck 8 ,
396.Xr mount 8 ,
397.Xr tunefs 8 ,
398.Xr vinum 8
399.Rs
400.%A M. McKusick
401.%A W. Joy
402.%A S. Leffler
403.%A R. Fabry
404.%T A Fast File System for UNIX
405.%J ACM Transactions on Computer Systems 2
406.%V 3
407.%P pp 181-197
408.%D August 1984
409.%O (reprinted in the BSD System Manager's Manual)
410.Re
411.Sh HISTORY
412The
413.Nm
414command appeared in
415.Bx 4.2 .