Main index | Section 8 | 日本語 | Options |
Options indicate an action to be performed:
| |
Attach a memory disk.
This will configure and attach a memory disk with the
parameters specified and attach it to the system.
If the
| |
| |
Detach a memory disk from the system and release all resources. | |
| |
Resize a memory disk. | |
| |
Select the type of the memory disk. | |
malloc | |
Storage for this type of memory disk is allocated with
malloc(9).
This limits the size to the malloc bucket limit in the kernel.
If the
| |
vnode |
A file specified with
|
swap | Storage for this type of memory disk is allocated from buffer memory. Pages get pushed out to swap when the system is under memory pressure, otherwise they stay in the operating memory. Using swap backing is generally preferred instead of using malloc backing. |
null | Bitsink; all writes do nothing, all reads return zeroes. |
| |
Filename to use for the vnode type memory disk.
The
| |
| |
List configured devices.
If given with
| |
| |
When printing md(4) device names, print only the unit number without the md(4) prefix. | |
| |
Size of the memory disk.
Size
is the number of 512 byte sectors unless suffixed with a
b, k, m, g, t,
or
p
which
denotes byte, kilobyte, megabyte, gigabyte, terabyte and petabyte respectively.
When used without the
| |
| |
Sectorsize to use for the memory disk, in bytes. | |
| |
See the description of the
| |
| |
For
malloc
or
vnode
backed devices, the
| |
| |
Associate a label (arbitrary string) with the new memory disk.
The label can then be inspected with
Fl | |
| |
Set or reset options. | |
[ no ] async | |
For vnode backed devices: avoid IO_SYNC for increased performance but at the risk of deadlocking the entire kernel. | |
[ no ] reserve | |
Allocate and reserve all needed storage from the start, rather than as needed. | |
[ no ] cluster | |
Enable clustering on this disk. | |
[ no ] compress | |
Enable/disable compression features to reduce memory usage. | |
[ no ] force | |
Disable/enable extra sanity checks to prevent the user from doing something
that might adversely affect the system.
This can be used with the
| |
[ no ] readonly | |
Enable/disable readonly mode. | |
[ no ] verify | |
For vnode backed devices: enable/disable requesting verification of the file used for backing store. The type of verification depends on which security features are available. One example of verification is testing file integrity with checksums or cryptographic signatures. | |
| |
Request a specific unit number or device name for the md(4) device instead of automatic allocation. If a device name is specified, it must start with "md" followed by the unit number. | |
The last form,
mdconfig
file,
is provided for convenience as an abbreviation of
mdconfig
mdconfig /tmp/boot.flp
Create a 1 gigabyte swap backed memory disk named "md3":
mdconfig -s 1g -u md3
Detach and free all resources used by /dev/md3:
mdconfig -du md3
Show detailed information on current memory disks:
mdconfig -lv
Resize the "md3" memory disk to 2 gigabytes:
mdconfig -rs 2g -u md3
Create a 1 gigabyte swap backed disk, initialize an ffs(7) file system on it, and mount it on /tmp:
mdconfig -s 1g -u md10 newfs -U /dev/md10 mount /dev/md10 /tmp chmod 1777 /tmp
Create a memory disk out of an ISO 9660 CD image file, using the first available md(4) device, and then mount it:
mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt
Create a file-backed device from a hard disk image that begins with 512K of raw header information. gnop(8) is used to skip over the header information, positioning md1.nop to the start of the filesystem in the image.
mdconfig -u md1 -f diskimage.img gnop create -o 512K md1 mount /dev/md1.nop /mnt
MDCONFIG (8) | November 6, 2020 |
Main index | Section 8 | 日本語 | Options |
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