From mboxrd@z Thu Jan 1 00:00:00 1970 From: imp@bsdimp.com (Warner Losh) Date: Fri, 12 May 2017 10:21:16 -0600 Subject: [TUHS] The evolution of Unix facilities and architecture In-Reply-To: <3aa087e2-9305-3d5b-123e-dc2d7833baf2@case.edu> References: <20170511140729.2262B18C09A@mercury.lcs.mit.edu> <013b01d2ca96$6901b370$3b051a50$@ronnatalie.com> <20170511222547.GJ4341@mcvoy.com> <1873b923-6f5e-83a2-753d-6d7a2f8b580a@telegraphics.com.au> <20170512081713.GD7265@yeono.kjorling.se> <0121AE71-2930-40AB-ABFD-552E207AF979@tfeb.org> <20170512143047.GV4341@mcvoy.com> <3aa087e2-9305-3d5b-123e-dc2d7833baf2@case.edu> Message-ID: On Fri, May 12, 2017 at 9:52 AM, Chet Ramey 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. https://www.usenix.org/publications/library/proceedings/sd93/seltzer.pdf 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. Warner