[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."


More information about the TUHS mailing list