Description of the Journaling topology
Martin P. Hellwig
mhellwig at xs4all.nl
Tue Dec 28 14:13:38 PST 2004
Matthew Dillon wrote:
Our journaling layer is designed to address these issues. Providing a
high level filesystem operations change stream off-site is far more
robust then providing a block device level change stream. Being able
to go off-site in real-time to a secure (or more secure) machine can't
be beat. Being able to rewind the journal to any point in time,
infinitely fine-grained, gives security managers and sysops and even
users an incredibly powerful tool for deconstructing security events
(e.g. log file erasures), recovering lost data, and so on and so forth.
These are very desireable traits, yah?
As a System Administrator I must say that this makes me pretty happy and
I mean <throw other technology out if I can have this>-happy, one of the
problems is see in my line of job is that I have such amount of data
that backup is not feasible anymore, what means the cost of the backup
is higher then the gain that you could recover data after an incident.
A friend of my works at a shop where the SA's have the problem that in
their environment data production is at a higher rate then the tape
rooms can write.
If I really want to throw someone for a loop I ask him whether he'd
rather be the guy inventing the algorithm and writing the paper, or
the guy implementing it from the paper. It's a question that forces
the questioner to actually think with his noggin.
I think that is really the crux of the problem... programmers have been
taught to build things from templates rather then build things from
concepts... and THAT is primarily why software is still stuck in the
dark ages insofar as I am concerned. True innovation requires having
lightbulbs go off above your head all the time, and you don't get that
from reading papers. Another amusing anecdote... every time I complained
about something in FreeBSD-5 or 6 the universal answer I got was that
'oh, well, Solaris did it this way' or 'there was a paper about this'
or a myrid of other 'someone else wrote it down so it must be good'
excuses. Not once did I ever get any other answer. Pretty sad, I think,
and also sadly not unique to FreeBSD. It's a problem with mindset, and
mindset is a problem with our educational system (the entire world's).
Most educational concepts are based on learning already present
experience, nobody is educated in motivating them self to learn for the
progress itself. This results in (besides others) not thinking outside
the box (papers) and relying on others to make a proof of concept for
any new technology.
Which reminds me that I don't know of any _working_ technology not being
first implemented and tested before the paper of it was written.
Inventing is trying, writing is understanding, reading is at the best a
Only the ones who learn to think for/by them self have the capability to
learn how to think outside the box, but the most falter at the first step.
I'm really happy that DragonFly has finally progressed to the point where
we can begin to implement our loftier goals. Up until now the work has
been primarily ripping out and reimplementing the guts of the system with
very little visibility poking through to the end-user. Now we are
are starting to push into things that have direct consequences to the
end-user. The journaling is one of the three major legs that will
support the ultimate goal of single-system-image clustering. The second
leg is a cache coherency scheme, and the third will be resource sharing
and migration. All three will have to be very carefully and deliberately
integrated together into a single whole to achieve the ultimate goal.
This makes journaling a major turning point for the project... one,
I hope, that attracts more people to DragonFly.
Is that primarily coders or users? For me I want to switch my servers to
DF but I am kind of waiting for a new release version where only the
bugs and exploits are updating but no more code is introduced.
I think that overall from what I see on my test server DF is production
ripe but I'm overly paranoid when dealing with productivity machines.
I'll planned to jump the ship from 4 to DF in July 2005 ( a matter of
backup and reinstalling the OS) do you think there will be new release
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