[TUHS] The evolution of Unix facilities and architecture

Warner Losh imp at bsdimp.com
Sat May 13 02:21:16 AEST 2017

On Fri, May 12, 2017 at 9:52 AM, Chet Ramey <chet.ramey at case.edu> wrote:
> On 5/12/17 10:30 AM, Larry McVoy wrote:
>> On Fri, May 12, 2017 at 02:56:59PM +0100, Tim Bradshaw wrote:
>>> When I found out about this I thought seriously of shorting Sun's
>>> stock (if I knew how to do that).  I would have made money.  As it was
>>> we stuck with logged UFS which, by 2007 or so was seriously bulletproof.
>> Wait, someone added logging to UFS?  Is there a writeup of that anywhere?
> You could look at the soft updates paper from 1999 for Kirk's perspective.
> https://www.usenix.org/legacy/event/usenix99/full_papers/mckusick/mckusick.pdf
> There was a paper about journaled soft updates, too:
> https://www.mckusick.com/softdep/suj.pdf

There's also Margo's paper on LFS, which added logging to UFS, though
by the time it was over it wasn't recognizable.


The Journaled updates, though, is that someone added an intent log to
UFS + SoftUpdates. This was used to replay the last few operations
when doing fsck coming back up after a crash. There's also something
called gjournal, which adds a different type of journaling to UFS, but
the less said about that train-wreck the better.


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