mdmfs broken? --> no, but md is broken!

[Jacques Garrigue]

Stijn Hoop wrote:
> What's the correct syntax in 5-CURRENT to have a memory disk for /tmp
> in your /etc/fstab?

Others have answerred as how it can be done.
However, I  must strongly inform you against using md on 5-CURRENT,
particularly for /tmp, has I found it dangerously buggy.

You can see the bug report below for details of the problem.
http://www.freebsd.org/cgi/query-pr.cgi?pr=47538

Basically, tar doesn't work properly on such a file system.
To verify it, you just have to write enough data on the memory file
system so as it is actually flushed to the disk. Then you start to see
discrepancies appearing. Curiously the problem doesn't appear with pax.

I verified this with 5.0-RELEASE, and also with 5.1-BETA on a
different machine with 256MB memory.

I hope this problem is solved soon, as I am a fan of memory mounted
/tmp like you.
I enjoyed also mounting file systems inside files on a msdos
partition with the vn driver, to avoid repartitioning, but this also
seems to be broken with md.

Cheers,

Jacques Garrigue