tmpmfs formal documentation

[alvaro]

is there any formal doc over the option

tmpmfs="YES"

in /etc/rc.conf?

what is the difference with using md or mfs in fstab?

 

[Beastie]

is there any formal doc over the option

tmpmfs="YES"

in /etc/rc.conf?

/etc/defaults/rc.conf (also check rc.conf(5)) says

[...]
tmpmfs="AUTO"		# Set to [highlight]YES to always create an mfs /tmp[/highlight], NO to never
[...]

what is the difference with using md or mfs in fstab?

The md(4) driver uses the mfs (or memory filesystem) to create a memory disk. The created MD just has a fixed location (/tmp). It also has a size option (set by tmpsize) and extra options (set by tmpmfs_flags) that you can override.

But you could create the MD anywhere you want (not just on /tmp) and with any additional option. See mdmfs(8) and the examples in it:

     Create and mount a 32 megabyte swap-backed file system on /tmp:

           mdmfs -s 32m md /tmp

     The same file system created as an entry in /etc/fstab:

           md /tmp mfs rw,-s32m 2 0

(simply change /tmp)

And alternatively you could use the tmpfs(5) driver to do the same on /tmp or anywhere else.