xref: /freebsd/sbin/mdmfs/mdmfs.8 (revision 77b7cdf1999ee965ad494fddd184b18f532ac91a)
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2.\" Copyright (c) 2001 Dima Dorfman.
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26.\" $FreeBSD$
27.\"
28.Dd August 5, 2001
29.Dt MDMFS 8
30.Os
31.Sh NAME
32.Nm mdmfs ,
33.Nm mount_mfs
34.Nd configure and mount an in-memory file system using the
35.Xr md 4
36driver
37.Sh SYNOPSIS
38.Nm
39.Op Fl DLMNSUX
40.Op Fl a Ar maxcontig
41.Op Fl b Ar block-size
42.Op Fl c Ar cylinders
43.Op Fl d Ar rotdelay
44.Op Fl e Ar maxbpg
45.Op Fl F Ar file
46.Op Fl f Ar frag-size
47.Op Fl i Ar bytes
48.Op Fl m Ar percent-free
49.Op Fl n Ar rotational-positions
50.Op Fl O Ar optimization
51.Op Fl o Ar mount-options
52.Op Fl p Ar permissions
53.Op Fl s Ar size
54.Op Fl v Ar version
55.Op Fl w Ar user : Ns Ar group
56.Ar md-device
57.Ar mount-point
58.Nm
59.Fl C
60.Op Fl NU
61.Op Fl a Ar maxcontig
62.Op Fl b Ar block-size
63.Op Fl c Ar cylinders
64.Op Fl d Ar rotdelay
65.Op Fl e Ar maxbpg
66.Op Fl F Ar file
67.Op Fl f Ar frag-size
68.Op Fl i Ar bytes
69.Op Fl m Ar percent-free
70.Op Fl n Ar rotational-positions
71.Op Fl O Ar optimization
72.Op Fl o Ar mount-options
73.Op Fl s Ar size
74.Op Fl v Ar version
75.Ar md-device
76.Ar mount-point
77.Sh DESCRIPTION
78The
79.Nm
80utility is designed to be a work-alike and look-alike of the deprecated
81.Xr mount_mfs 8 .
82The end result is essentially the same,
83but is accomplished in a completely different way.
84The
85.Nm
86utility configures an
87.Xr md 4
88disk using
89.Xr mdconfig 8 ,
90puts a UFS file system on it using
91.Xr newfs 8 ,
92and mounts it using
93.Xr mount 8 .
94All the command line options are passed to the appropriate program
95at the appropriate stage in order to achieve the desired effect.
96.Pp
97By default,
98.Nm
99creates a swap-based
100.Pq Dv MD_SWAP
101disk with soft-updates enabled
102and mounts it on
103.Ar mount-point .
104It uses the
105.Xr md 4
106device specified by
107.Ar md-device .
108If
109.Ar md-device
110is
111.Ql md
112(no unit number),
113it will use
114.Xr md 4 Ns 's
115auto-unit feature to automatically select an unused device.
116Unless otherwise specified with one of the options below,
117it uses the default arguments to all the helper programs.
118.Pp
119The following options are available.
120Where possible,
121the option letter matches the one used by
122.Xr mount_mfs 8
123for the same thing.
124.Bl -tag -width indent
125.It Fl a Ar maxcontig
126Specify the maximum number of contiguous blocks that will be laid
127out before forcing a rotational delay
128(see the
129.Fl d
130option).
131.It Fl b Ar block-size
132The block size of the file system, in bytes.
133.It Fl C
134Enable full compatibility mode with
135.Xr mount_mfs 8 .
136See the
137.Sx COMPATIBILITY
138section for more information.
139.It Fl c Ar cylinders
140The number of cylinders per cylinder group in the file system.
141.It Fl D
142If not using auto-unit,
143do not run
144.Xr mdconfig 8
145to try to detach the unit before attaching it.
146.It Fl d Ar rotdelay
147Specify the minimum time in milliseconds required to initiate another
148disk transfer on the same cylinder.
149Modern disks with read/write-behind achieve higher performance without
150this feature,
151so it is best to leave it at 0 milliseconds.
152.It Fl e Ar maxbpg
153Indicate the maximum number of blocks any single file can allocate
154out of a cylinder group before it is forced to begin allocating
155blocks from another cylinder group.
156.It Fl F Ar file
157Create a vnode-backed
158.Pq Dv MD_VNODE
159memory disk backed by
160.Ar file .
161.It Fl f Ar frag-size
162The fragment size of the file system in bytes.
163.It Fl i Ar bytes
164Number of bytes per inode.
165.It Fl L
166Show the output of the helper programs.
167By default,
168it is sent to
169.Pa /dev/null .
170.It Fl M
171Create a
172.Xr malloc 9
173backed disk
174.Pq Dv MD_MALLOC
175instead of a swap-backed disk.
176.It Fl m Ar percent-free
177The percentage of space reserved for the superuser.
178.It Fl N
179Do not actually run the helper programs.
180This is most useful in conjunction with
181.Fl X .
182.It Fl n Ar rotational-positions
183The default number of rotational positions to distinguish.
184.It Fl O Ar optimization
185Select the optimization preference;
186valid choices are
187.Cm space
188and
189.Cm time ,
190which will optimize for minimum space fragmentation and
191minimum time spent allocating blocks,
192respectively.
193.It Fl o Ar mount-options
194Specify the mount options with which to mount the file system.
195See
196.Xr mount 8
197for more information.
198.It Fl p Ar permissions
199Set the file (directory) permissions of the mount point
200.Ar mount-point
201to
202.Ar permissions .
203.It Fl S
204Do not enable soft-updates on the file system.
205.It Fl s Ar size
206Specify the size of the disk to create.
207This only makes sense if
208.Fl F
209is
210.Em not
211specified.
212That is,
213this will work for the default swap-backed
214.Pq Dv MD_SWAP
215disks,
216and the optional
217.Pq Fl M
218.Xr malloc 9
219backed disks
220.Pq Dv MD_MALLOC .
221.It Fl U
222Enable soft-updates on the file system.
223This is the default, even in compatibility mode, and is accepted only
224for compatibility.
225It is only really useful to negate the
226.Fl S
227flag, should such a need occur.
228.It Fl v Ar version
229Specify the UFS version number for use on the file system; it may be
230either
231.Dv 1
232or
233.Dv 2 .
234The default is derived from the default of the
235.Xr newfs 8
236command.
237.It Fl w Ar user : Ns Ar group
238Set the owner and group to
239.Ar user
240and
241.Ar group ,
242respectively.
243The arguments have the same semantics as with
244.Xr chown 8 ,
245but specifying just a
246.Ar user
247or just a
248.Ar group
249is not supported.
250.It Fl X
251Print what command will be run before running it, and
252other assorted debugging information.
253.El
254.Pp
255The
256.Fl F
257and
258.Fl s
259options are passed to
260.Xr mdconfig 8
261as
262.Fl f
263and
264.Fl s ,
265respectively.
266The
267.Fl a , b , c , d , e , f , i , m
268and
269.Fl n
270options are passed to
271.Xr newfs 8
272with the same letter;
273the
274.Fl O
275option is passed to
276.Xr newfs 8
277as
278.Fl o .
279The
280.Fl o
281option is passed to
282.Xr mount 8
283with the same letter.
284See the programs that the options are passed to for more information
285on their semantics.
286.Sh EXAMPLES
287Create and mount a 32 megabyte swap-backed file system on
288.Pa /tmp :
289.Pp
290.Dl "mdmfs -s 32m md /tmp"
291.Pp
292Create and mount a 16 megabyte malloc-backed file system on
293.Pa /tmp
294using the
295.Pa /dev/md1
296device;
297furthermore,
298do not use soft-updates on it and mount it
299.Cm async :
300.Pp
301.Dl "mdmfs -M -S -o async -s 16m md1 /tmp"
302.Sh COMPATIBILITY
303The
304.Nm
305utility, while designed to be fully compatible with
306.Xr mount_mfs 8 ,
307can be useful by itself.
308Since
309.Xr mount_mfs 8
310had some silly defaults, a
311.Dq full compatibility
312mode is provided for the case where bug-to-bug compatibility is desired.
313.Pp
314Full compatibility is enabled with the
315.Fl C
316flag,
317or by starting
318.Nm
319with the name
320.Li mount_mfs
321or
322.Li mfs
323(as returned by
324.Xr getprogname 3 ) .
325In this mode, only the options which would be accepted by
326.Xr mount_mfs 8
327are valid.
328Furthermore, the following behavior, as done by
329.Xr mount_mfs 8 ,
330is duplicated:
331.Bl -bullet -offset indent
332.It
333The file mode of
334.Ar mount-point
335is set to
336.Li 01777
337as if
338.Fl p Ar 1777
339was given on the command line.
340.El
341.Sh SEE ALSO
342.Xr md 4 ,
343.Xr fstab 5 ,
344.Xr mdconfig 8 ,
345.Xr mount 8 ,
346.Xr newfs 8
347.Sh AUTHORS
348.An Dima Dorfman
349