From mboxrd@z Thu Jan 1 00:00:00 1970 From: lm@mcvoy.com (Larry McVoy) Date: Thu, 11 May 2017 17:21:12 -0700 Subject: [TUHS] The evolution of Unix facilities and architecture In-Reply-To: <017001d2cab1$16bcf4b0$4436de10$@ronnatalie.com> References: <20170511140729.2262B18C09A@mercury.lcs.mit.edu> <013b01d2ca96$6901b370$3b051a50$@ronnatalie.com> <20170511222547.GJ4341@mcvoy.com> <017001d2cab1$16bcf4b0$4436de10$@ronnatalie.com> Message-ID: <20170512002112.GR4341@mcvoy.com> Yeah, I get ordered writes, I taught a CS course at Stanford and I made my students learn all about them. I'm a UFS guy, so far as I know I'm the last guy to push UFS/FFS forward (which is sort of sad). The Linux stuff is better. It just is. And we should all respect that, I know we sit around and love on ancient Unix, and believe me, I love that stuff it changed the world, but we should respect people who have moved it past what Unix did. And I think Linux moved the file system past what Unix did. --lm On Thu, May 11, 2017 at 07:48:27PM -0400, Ron Natalie wrote: > Ordered writes go back to the original BSD fast file system, no? I seem > to recall that when we switched from our V6/V7 disks, > the filesystem got a lot more stable in crashes. > > -----Original Message----- > From: TUHS [mailto:tuhs-bounces at minnie.tuhs.org] On Behalf Of Dave Horsfall > Sent: Thursday, May 11, 2017 7:47 PM > To: The Eunuchs Hysterical Society > Subject: Re: [TUHS] The evolution of Unix facilities and architecture > > On Thu, 11 May 2017, Larry McVoy wrote: > > [...] > > > Try the same thing with Linux. The file system will come back, > > starting with, I believe, ext2. > > That's a journalled FS, isn't it? In which case the transactions get > replayed. > > > My belief is that Linux orders writes such that while you may lose > > data (as in, a process created a file, the OS said it was OK, but that > > file will not be in the file system after a crash), but the rest of > > the file system will be consistent. I think it's as if you powered > > off the machine a few seconds earlier than you actually did, some > > stuff is in flight and until they can write stuff out in the proper > > order you may lose data on a hard reset. > > And FreeBSD (at least) has been doing ordered writes for quite some time. > > -- > Dave Horsfall DTM (VK2KFU) "Those who don't understand security will > suffer." -- --- Larry McVoy lm at mcvoy.com http://www.mcvoy.com/lm