12 May
2017
12 May
'17
1:05 a.m.
On 2017-05-11 7:47 PM, Dave Horsfall wrote:
On Thu, 11 May 2017, Larry McVoy wrote:
[...]
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
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.