Attach a memory disk. This will configure and attach a memory disk with the parameters specified and attach it to the system.
-d
Detach a memory disk from the system and release all resources.
-t type
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 -o reserve option is not set, creating and filling a large malloc-backed memory disk is a very easy way to panic a system.
vnode
A file specified with -f file becomes the backingstore for this memory disk.
swap
Swap space is used to back this memory disk.
-f file
Filename to use for the vnode type memory disk.
-l
List configured devices. If given with -u , display details about that particular device.
-n
When printing md device names, print only the unit number without the md prefix.
-s size
Size of the memory disk. Size is the number of 512 byte sectors unless suffixed with a b, k, m, g, or t which denotes byte, kilobyte, megabyte, gigabyte and terabyte respectively.
-S sectorsize
Sectorsize to use for malloc backed device.
-x sectors/track
See the description of the -y option below.
-y heads/cylinder
For malloc or vnode backed devices, the -x and -y options can be used to specify a synthetic geometry. This is useful for constructing bootable images for later download to other devices.
-o [nooption]
Set or reset options.
[noasync]
For vnode backed devices: avoid IO_SYNC for increased performance but at the risk of deadlocking the entire kernel.
[noreserve]
Allocate and reserve all needed storage from the start, rather than as needed.
[nocluster]
Enable clustering on this disk.
[nocompress]
Enable/Disable compression features to reduce memory usage.
[noforce]
Disable/Enable extra sanity checks to prevent the user from doing something that might adversely affect the system.
[noreadonly]
Enable/Disable readonly mode.
-u unit
Request a specific unit number for the md(4) device instead of automatic allocation.
