On Wed, Nov 11, 2009 at 12:24:25PM +0100, Janne Johansson wrote: > Nick Guenther wrote: > > >>>> So, as nicely summarized at > >>>> > > http://www.h-online.com/open/news/item/Possible-data-loss-in-Ext4-740467.html > > , > >>>> ext4 is kind of broken. It won't honor fsync and, as a /feature/, will > >>>> wait up to two minutes to write out data, leading to lots of files > >>>> emptied to the great bitbucket in the sky if the machine goes down in > >>>> that period. > >> There is a very simple explanation for why things are so. > >> Actual data file loss has never been what these things were coded for. > >> filesystem *tree and meta-data*, ie. the structure of how things are > >> knit together, is the main concern. If you lose the filesystem tree > >> structure, you've lost all your files, not just the newest ones. > >> Therefore the goal is safe metadata handling. The result is you can > >> lose specific data in specific (newly written to) files, but the > >> structure of the filesystem is consistant enough for fsck to not damage > >> it. > > > 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? > > It seems like some posters in this thread somehow misses the fact that > if you have outstanding writes and the box dies. Some of your data dies > also. New or old data, something will be missing.
And that all SATA drives enable it or else they are glacial and that SCSI disables it to enhance perception that one is safer. Buy a ups! your laptop has a built in one.
