From mboxrd@z Thu Jan 1 00:00:00 1970 From: toby@telegraphics.com.au (Toby Thain) Date: Thu, 11 May 2017 21:05:55 -0400 Subject: [TUHS] The evolution of Unix facilities and architecture In-Reply-To: References: <20170511140729.2262B18C09A@mercury.lcs.mit.edu> <013b01d2ca96$6901b370$3b051a50$@ronnatalie.com> <20170511222547.GJ4341@mcvoy.com> Message-ID: <1873b923-6f5e-83a2-753d-6d7a2f8b580a@telegraphics.com.au> On 2017-05-11 7:47 PM, Dave Horsfall wrote: > 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. No, I think ext3fs was the first version that was journaled. So was reiserfs. With pull-plug tests I could get ext3fs to toss cookies but not reiserfs. Now of course the state of the art is copy-on-write, like ZFS. --Toby > >> 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. >