/.journal ... whazzat?

[Lynn David Newton]

I just discovered a 33MB file in my root directory
named /.journal, dated March 26 of this year, which
would have been about the time I upgraded to RH 7.2
(from 7.1) which is probably also the time I converted
to ext3 filesystems. I'm guessing this file is some
sort of object that keeps the now-journaled filesystem
in order, but I don't know that. Can someone identify
this file for me and give a high-level explanation of
what it does?

If it's what it appears to be, that's a pretty hefty
piece of disk size to sacrifice to ext3. Wouldn't want
to live without jfs, though.

There is no such file in /home, which is mounted and
also type ext3, so I suppose if this thing is
journaling overhead, it must be designed to handle all
slices on the local system. (That's a question in the
form of a hypothesis.)

Inquiring minds want to know.

-- 
Lynn David Newton
Phoenix, AZ