1 .\" Copyright (c) 1993 University of Utah.
2 .\" Copyright (c) 1980, 1989, 1991, 1993
3 .\" The Regents of the University of California. All rights reserved.
5 .\" Poul-Henning Kamp All rights reserved.
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35 .\" @(#)vnconfig.8 8.1 (Berkeley) 6/5/93
36 .\" from: src/usr.sbin/vnconfig/vnconfig.8,v 1.19 2000/12/27 15:30:29
45 .Nd configure and enable memory disks
51 .Oo Fl o Oo Cm no Oc Ns Ar option Oc ...
54 .Op Fl S Ar sectorsize
56 .Op Fl x Ar sectors/track
57 .Op Fl y Ar heads/cylinder
61 .Op Fl o Oo Cm no Oc Ns Ar force
66 .Op Fl o Oo Cm no Oc Ns Ar force
78 utility configures and enables
82 Options indicate an action to be performed:
83 .Bl -tag -width indent
86 This will configure and attach a memory disk with the
87 parameters specified and attach it to the system.
90 option is not provided, the newly created device name will be printed on stdout.
92 Detach a memory disk from the system and release all resources.
96 Select the type of the memory disk.
97 .Bl -tag -width "malloc"
99 Storage for this type of memory disk is allocated with
101 This limits the size to the malloc bucket limit in the kernel.
104 option is not set, creating and filling a large
105 malloc-backed memory disk is a very easy way to
108 A file specified with
110 becomes the backing store for this memory disk.
112 Storage for this type of memory disk is allocated from buffer
114 Pages get pushed out to swap when the system is under memory
115 pressure, otherwise they stay in the operating memory.
118 backing is generally preferred instead of using
122 Bitsink; all writes do nothing, all reads return zeroes.
125 Filename to use for the vnode type memory disk.
130 options are implied if not specified.
132 List configured devices.
135 display details about that particular device.
140 device names of which
142 is used as the backing store.
147 options are specified,
148 display devices which match the two conditions.
151 option is specified, show all details.
155 device names, print only the unit number without the
159 Size of the memory disk.
161 is the number of 512 byte sectors unless suffixed with a
166 denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively.
171 options are implied if not specified.
172 .It Fl S Ar sectorsize
173 Sectorsize to use for the memory disk, in bytes.
174 .It Fl x Ar sectors/track
175 See the description of the
178 .It Fl y Ar heads/cylinder
187 options can be used to specify a synthetic geometry.
188 This is useful for constructing bootable images for later download to
190 .It Fl o Oo Cm no Oc Ns Ar option
191 Set or reset options.
192 .Bl -tag -width indent
193 .It Oo Cm no Oc Ns Cm async
196 backed devices: avoid
198 for increased performance but
199 at the risk of deadlocking the entire kernel.
200 .It Oo Cm no Oc Ns Cm reserve
201 Allocate and reserve all needed storage from the start, rather than as needed.
202 .It Oo Cm no Oc Ns Cm cluster
203 Enable clustering on this disk.
204 .It Oo Cm no Oc Ns Cm compress
205 Enable/disable compression features to reduce memory usage.
206 .It Oo Cm no Oc Ns Cm force
207 Disable/enable extra sanity checks to prevent the user from doing something
208 that might adversely affect the system.
209 .It Oo Cm no Oc Ns Cm readonly
210 Enable/disable readonly mode.
213 Request a specific unit number or device name for the
215 device instead of automatic allocation.
216 If a device name is specified, it must be start with
218 followed by the unit number.
224 is provided for convenience as an abbreviation of
233 The name of the allocated unit will be printed on stdout, such as
236 .Dl mdconfig -a -t malloc -s 4m
244 .Dl mdconfig -a -t vnode -f /tmp/boot.flp -u md4
246 Detach and free all resources used by
249 .Dl mdconfig -d -u md4
251 Create a 128MByte swap backed disk, initialize an
253 file system on it, and mount it on
255 .Bd -literal -offset indent
256 mdconfig -a -t swap -s 128M -u md10
262 Create a 5MB file-backed disk
268 .Bd -literal -offset indent
269 dd if=/dev/zero of=somebackingfile bs=1k count=5k
270 mdconfig -f somebackingfile -u md0
278 device out of an ISO 9660 CD image file
283 .Pc , using the first available
285 device, and then mount the new memory disk:
286 .Bd -literal -offset indent
287 mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt
290 Create a file-backed device from a hard disk image that begins
291 with 512K of raw header information.
293 is used to skip over the header information, positioning
295 to the start of the filesystem in the image.
296 .Bd -literal -offset indent
297 mdconfig -f diskimage.img -u md1
298 gnop create -o 512K md1
299 mount /dev/md1.nop /mnt
311 utility first appeared in
313 as a cleaner replacement for the
321 utility was written by
322 .An Poul-Henning Kamp Aq Mt phk@FreeBSD.org .