[unix-history] / usr / src / sbin / newfs / newfs.8

.\" Copyright (c) 1983, 1987, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)newfs.8	6.10 (Berkeley) 3/16/91
.\"
.Dd March 16, 1991
.Dt NEWFS 8
.Os BSD 4.2
.Sh NAME
.Nm newfs ,
.Nm mfs
.Nd construct a new file system
.Sh SYNOPSIS
.Nm newfs
.Op Fl N
.Op Ar newfs-options
.Ar special
.Nm mfs
.Op Fl F Ar mount_flags
.Op Ar newfs-options
.Ar special node
.Sh DESCRIPTION
.Nm Newfs
replaces the more obtuse
.Xr mkfs 8
program.
Before running 
.Nm newfs
or
.Nm mfs ,
the disk must be labeled using 
.Xr disklabel 8 .
.Nm Newfs
builds a file system on the specified special device
basing its defaults on the information in the disk label.
Typically the defaults are reasonable, however
.Nm newfs
has numerous options to allow the defaults to be selectively overridden.
.Pp
.Nm Mfs
is used to build a file system in virtual memory and then mount it
on a specified node.
.Nm Mfs
exits and the contents of the file system are lost
when the file system is unmounted.
If
.Nm mfs
is sent a signal while running,
for example during system shutdown,
it will attempt to unmount its
corresponding file system.
The parameters to
.Nm mfs
are the same as those to
.Nm newfs .
The special file is only used to read the disk label which provides
a set of configuration parameters for the memory based file system.
The special file is typically that of the primary swap area,
since that is where the file system will be backed up when
free memory gets low and the memory supporting
the file system has to be paged.
.Pp
The following options define the general layout policies.
.Bl -tag -width Fl
.It Fl N
Causes the file system parameters to be printed out
without really creating the file system.
.It Fl b Ar block-size
The block size of the file system in bytes.  
.It Fl f Ar frag-size
The fragment size of the file system in bytes.
.It Fl m Ar free space \&%
The percentage of space reserved from normal users; the minimum
free space threshold.  The default value used is 10%.
See
.Xr tunefs 8
for more details on how to set this option.
.It Fl o Ar optimization\ preference
.Pq ``space'' or ``time''
The file system can either be instructed to try to minimize the time spent
allocating blocks, or to try to minimize the space fragmentation on the disk.
If the value of minfree (see above) is less than 10%,
the default is to optimize for space;
if the value of minfree greater than or equal to 10%,
the default is to optimize for time.
See
.Xr tunefs 8
for more details on how to set this option.
.It Fl a Ar maxcontig
This specifies the maximum number of contiguous blocks that will
be laid out before forcing a rotational delay (see
.Fl d
below).
The default value is one.
See
.Xr tunefs 8
for more details on how to set this option.
.It Fl d Ar rotdelay
This specifies the expected time (in milliseconds)
to service a transfer completion
interrupt and initiate a new transfer on the same disk.
The default is 4 milliseconds.
See
.Xr tunefs 8
for more details on how to set this option.
.It Fl e Ar maxbpg
This indicates the maximum number of blocks any single file can
allocate out of a cylinder group before it is forced to begin
allocating blocks from another cylinder group.
The default is about one quarter of the total blocks in a cylinder group.
See
.Xr tunefs 8
for more details on how to set this option.
.It Fl i Ar number of bytes per inode
This specifies the density of inodes in the file system.
The default is to create an inode for each 2048 bytes of data space.
If fewer inodes are desired, a larger number should be used;
to create more inodes a smaller number should be given.
.It Fl c Ar #cylinders/group
The number of cylinders per cylinder group in a file system.
The default value used is 16.
.It Fl s Ar size
The size of the file system in sectors.
.Pp
The following options override the standard sizes for the disk geometry. 
Their default values are taken from the disk label.
Changing these defaults is useful only when using
.Nm newfs
to build a file system whose raw image will eventually be used
on a different type of disk than the one on which it is initially
created (for example on a write-once disk).
Note that changing any of these values from their
defaults will make it impossible for 
.Xr fsck
to find the alternate superblocks if the standard super block is lost.
.It Fl r Ar revolutions/minute
The speed of the disk in revolutions per minute.
.It Fl S Ar sector-size
The size of a sector in bytes (almost never anything but 512).
.It Fl u Ar sectors/track
The number of sectors per track available for data
allocation by the file system.  This does not
include sectors reserved at the end of each track
for bad block replacement (see
.Fl p
below).
.It Fl t Ar #tracks/cylinder
The number of tracks/cylinder available for data
allocation by the file system.
.It Fl p Ar spare sectors per track
Spare sectors (bad sector replacements) are physical sectors
that occupy space at the end of each track.
They are not counted as part of the sectors/track
.Pq Fl u
since they are not available to the file system for data allocation.
.It Fl x Ar spare sectors per cylinder
Spare sectors (bad sector replacements) are physical sectors
that occupy space at the end of the last track in the cylinder.
They are deducted from the sectors/track
.Pq Fl u
of the last track of each cylinder
since they are not available to the file system for data allocation.
.It Fl l Ar hardware sector interleave
Used to describe perturbations in the media format to
compensate for a slow controller.
Interleave is physical sector interleave on each track,
specified as the denominator of the ratio:
.Dl sectors read/sectors passed over
Thus an interleave of 1/1 implies contiguous layout, while 1/2
implies logical sector 0 is separated by one sector from logical
sector 1.
.It Fl k Ar sector \&0 skew , per track
Used to describe perturbations in the media format to
compensate for a slow controller.
Track skew is the offset of sector 0 on track N
relative to sector 0 on track N-1 on the same cylinder.
.Pp
.El
The following option applies only to
.Nm mfs .
.Bl -tag -width Fl
.It Fl F Ar mount flags
Used to pass in a decimal numeric value to be passed
as mount flags when running as a memory based file system.
This option is primarily intended for use when
.Nm mfs
is started by the
.Xr mount 8
command.
.El
.Sh SEE ALSO
.Xr disktab 5 ,
.Xr fs 5 ,
.Xr disklabel 8 ,
.Xr diskpart 8 ,
.Xr fsck 8 ,
.Xr format 8 ,
.Xr tunefs 8
.Rs
.%A M. McKusick
.%A W. Joy
.%A S. Leffler
.%A R. Fabry
.%T A Fast File System for UNIX ,
.%J ACM Transactions on Computer Systems 2
.%V 3
.%P pp 181-197
.%D August 1984
.%O (reprinted in the BSD System Manager's Manual)
.Re
.Sh HISTORY
The
.Nm
command appeared in
.Bx 4.2 .
Commit	Line	Data
5f726aec WJ	1	.\" Copyright (c) 1983, 1987, 1991 The Regents of the University of California.
	2	.\" 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 6.10 (Berkeley) 3/16/91
	33	.\"
	34	.Dd March 16, 1991
	35	.Dt NEWFS 8
	36	.Os BSD 4.2
	37	.Sh NAME
	38	.Nm newfs ,
	39	.Nm mfs
	40	.Nd construct a new file system
	41	.Sh SYNOPSIS
	42	.Nm newfs
	43	.Op Fl N
	44	.Op Ar newfs-options
	45	.Ar special
	46	.Nm mfs
	47	.Op Fl F Ar mount_flags
	48	.Op Ar newfs-options
	49	.Ar special node
	50	.Sh DESCRIPTION
	51	.Nm Newfs
	52	replaces the more obtuse
	53	.Xr mkfs 8
	54	program.
	55	Before running
	56	.Nm newfs
	57	or
	58	.Nm mfs ,
	59	the disk must be labeled using
	60	.Xr disklabel 8 .
	61	.Nm Newfs
	62	builds a file system on the specified special device
	63	basing its defaults on the information in the disk label.
	64	Typically the defaults are reasonable, however
65	.Nm newfs
66	has numerous options to allow the defaults to be selectively overridden.
67	.Pp
68	.Nm Mfs
69	is used to build a file system in virtual memory and then mount it
70	on a specified node.
71	.Nm Mfs
72	exits and the contents of the file system are lost
73	when the file system is unmounted.
74	If
75	.Nm mfs
76	is sent a signal while running,
77	for example during system shutdown,
78	it will attempt to unmount its
79	corresponding file system.
80	The parameters to
81	.Nm mfs
82	are the same as those to
83	.Nm newfs .
84	The special file is only used to read the disk label which provides
85	a set of configuration parameters for the memory based file system.
86	The special file is typically that of the primary swap area,
87	since that is where the file system will be backed up when
88	free memory gets low and the memory supporting
89	the file system has to be paged.
90	.Pp
91	The following options define the general layout policies.
92	.Bl -tag -width Fl
93	.It Fl N
94	Causes the file system parameters to be printed out
95	without really creating the file system.
96	.It Fl b Ar block-size
97	The block size of the file system in bytes.
98	.It Fl f Ar frag-size
99	The fragment size of the file system in bytes.
100	.It Fl m Ar free space \&%
101	The percentage of space reserved from normal users; the minimum
102	free space threshold. The default value used is 10%.
103	See
104	.Xr tunefs 8
105	for more details on how to set this option.
106	.It Fl o Ar optimization\ preference
107	.Pq ``space'' or ``time''
108	The file system can either be instructed to try to minimize the time spent
109	allocating blocks, or to try to minimize the space fragmentation on the disk.
110	If the value of minfree (see above) is less than 10%,
111	the default is to optimize for space;
112	if the value of minfree greater than or equal to 10%,
113	the default is to optimize for time.
114	See
115	.Xr tunefs 8
116	for more details on how to set this option.
117	.It Fl a Ar maxcontig
118	This specifies the maximum number of contiguous blocks that will
119	be laid out before forcing a rotational delay (see
120	.Fl d
121	below).
122	The default value is one.
123	See
124	.Xr tunefs 8
125	for more details on how to set this option.
126	.It Fl d Ar rotdelay
127	This specifies the expected time (in milliseconds)
128	to service a transfer completion
129	interrupt and initiate a new transfer on the same disk.
130	The default is 4 milliseconds.
131	See
132	.Xr tunefs 8
133	for more details on how to set this option.
134	.It Fl e Ar maxbpg
135	This indicates the maximum number of blocks any single file can
136	allocate out of a cylinder group before it is forced to begin
137	allocating blocks from another cylinder group.
138	The default is about one quarter of the total blocks in a cylinder group.
139	See
140	.Xr tunefs 8
141	for more details on how to set this option.
142	.It Fl i Ar number of bytes per inode
143	This specifies the density of inodes in the file system.
144	The default is to create an inode for each 2048 bytes of data space.
145	If fewer inodes are desired, a larger number should be used;
146	to create more inodes a smaller number should be given.
147	.It Fl c Ar #cylinders/group
148	The number of cylinders per cylinder group in a file system.
149	The default value used is 16.
150	.It Fl s Ar size
151	The size of the file system in sectors.
152	.Pp
153	The following options override the standard sizes for the disk geometry.
154	Their default values are taken from the disk label.
155	Changing these defaults is useful only when using
156	.Nm newfs
157	to build a file system whose raw image will eventually be used
158	on a different type of disk than the one on which it is initially
159	created (for example on a write-once disk).
160	Note that changing any of these values from their
161	defaults will make it impossible for
162	.Xr fsck
163	to find the alternate superblocks if the standard super block is lost.
164	.It Fl r Ar revolutions/minute
165	The speed of the disk in revolutions per minute.
166	.It Fl S Ar sector-size
167	The size of a sector in bytes (almost never anything but 512).
168	.It Fl u Ar sectors/track
169	The number of sectors per track available for data
170	allocation by the file system. This does not
171	include sectors reserved at the end of each track
172	for bad block replacement (see
173	.Fl p
174	below).
175	.It Fl t Ar #tracks/cylinder
176	The number of tracks/cylinder available for data
177	allocation by the file system.
178	.It Fl p Ar spare sectors per track
179	Spare sectors (bad sector replacements) are physical sectors
180	that occupy space at the end of each track.
181	They are not counted as part of the sectors/track
182	.Pq Fl u
183	since they are not available to the file system for data allocation.
184	.It Fl x Ar spare sectors per cylinder
185	Spare sectors (bad sector replacements) are physical sectors
186	that occupy space at the end of the last track in the cylinder.
187	They are deducted from the sectors/track
188	.Pq Fl u
189	of the last track of each cylinder
190	since they are not available to the file system for data allocation.
191	.It Fl l Ar hardware sector interleave
192	Used to describe perturbations in the media format to
193	compensate for a slow controller.
194	Interleave is physical sector interleave on each track,
195	specified as the denominator of the ratio:
196	.Dl sectors read/sectors passed over
197	Thus an interleave of 1/1 implies contiguous layout, while 1/2
198	implies logical sector 0 is separated by one sector from logical
199	sector 1.
200	.It Fl k Ar sector \&0 skew , per track
201	Used to describe perturbations in the media format to
202	compensate for a slow controller.
203	Track skew is the offset of sector 0 on track N
204	relative to sector 0 on track N-1 on the same cylinder.
205	.Pp
206	.El
207	The following option applies only to
208	.Nm mfs .
209	.Bl -tag -width Fl
210	.It Fl F Ar mount flags
211	Used to pass in a decimal numeric value to be passed
212	as mount flags when running as a memory based file system.
213	This option is primarily intended for use when
214	.Nm mfs
215	is started by the
216	.Xr mount 8
217	command.
218	.El
219	.Sh SEE ALSO
220	.Xr disktab 5 ,
221	.Xr fs 5 ,
222	.Xr disklabel 8 ,
223	.Xr diskpart 8 ,
224	.Xr fsck 8 ,
225	.Xr format 8 ,
226	.Xr tunefs 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
240	The
241	.Nm
242	command appeared in
243	.Bx 4.2 .