On 20.12.2012 09:43, Dave Chinner wrote: > On Wed, Dec 19, 2012 at 02:04:45AM +0100, Matthias Schniedermeyer wrote: > > > At least i'd count a dropped connection or power failure (The only > > difference is that in the latter case the cache MAY get dropped, > > otherwise i'd say both cases are basically the same) among the basic > > functionality that should be assured by a journaling fileystem. > > A journalling filesystem doesn't guarantee that you won't lose any > data on crash, power fail or permanent IO errors. All journalling > guarantees is that the filesystem is *consistent* after recovery. > i.e. you don't have to run xfs_repair after such a failure to > ensure it is not corrupted. In all your testing, you have not seen > the filesystem become corrupted, so the journalling has fulfilled > it's guarantee. I know that the basic property of the Journaling is to prevent corruption of the metadata, IOW to prevent exessive time to check fs after for e.g. a power-failure. I'm not arguing that a Journaling FS can't loose any data, only that it stays "within reason". I think you can agree that hunderds of files containing hundreds of gigabytes of data is well outside "reasonable looses". It doesn't have to be a pony or unicorn, but it should at least be a mule. :-) Overall i'm quite satisfied with the performance of XFS over the years, otherwise it wouldn't be the filesystem for over 99.999% of all the storage capacity i have. The only thing for which i don't use XFS are "/boot"-partitions, which amount to a few hundreds of MB, whereas XFS accounts for well over 100TB. About corruptions: I haven't had any corruption in my dozens of tests, BUT once my metdadata got corrupted by this bug! (Or mayby the umount-thing that you meantioned) It was the first time ever that i had to use xfs_repair (XFS refused to mount the fs) and i have been using XFS pretty much since it got ported to Linux. I "lost" a few files that i had to recover from my last backup (i didn't bother to look through lost+found). Which luckily i made just minutes before rebooting the machine in question. I had thought about issuing a 'sync', because the previous incarnation of the bug flashed before my inner eye. But by the time i had shutdown X and got to the command-prompt i had already forgotten to type 'sync' and went straight for 'reboot' and was slightly irritated when my machine did finished booting correctly, because a secondary-filesystem was MIA. (The root-filesystem was OK, but my /home was MIA) The most "pain" i can remeber before this episode was the 0-fill "thing", which bit me at least once. Other than that it's been smooth sailing all these years. I other words: Overall it's still very good work and i will rely on XFS for the forseable future. -- Matthias _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
