[TUHS] The evolution of Unix facilities and architecture
Dave Horsfall
dave at horsfall.org
Fri May 12 09:47:01 AEST 2017
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."
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