On Tue, Nov 10, 2009 at 10:50 PM, Nick Guenther <kou...@gmail.com> wrote: > See, since it seems that BSD doesn't have this file-data consistency > guarantee, are Linus' worries about ext4's potential data loss just > being alarmist? It seems to me that the case described in > https://bugs.edge.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/45 > is just as likely to happen on OpenBSD--if I run KDE or GNOME and mess > around with my settings then quickly murder the system the files will > be resurrected empty, right?
Yes, if you cut power before things are written to disk, they will not be written to disk. Snark aside, it really is that simple. Different filesystems have different definitions of what "written to disk means", or more accurately, *when*, but in all cases, if you cared you used fsync or tried a little harder to not crash. > Additionally FFS has the async flag which turns off the internal > consistency of the metadata structures; I guess there's no equivalent > for this in ext? The default in ext2 was async. ext3/4 are journaled, so a little different. > What is the reason softdep isn't on by default? It changes the "expected" behavior. FFS without softdep is a lot closer to the semantics people and most applications expect.
