On 9-Feb-09, at 6:17 PM, Miles Nordin wrote: >>>>>> "ok" == Orvar Korvar <knatte_fnatte_tja...@yahoo.com> writes: > > ok> You are not using ZFS correctly. > ok> You have misunderstood how it is used. If you dont follow the > ok> manual (which you havent) then any filesystem will cause > ok> problems and corruption, even ZFS or ntfs or FAT32, etc. You > ok> must use ZFS correctly. Start by reading the manual. > > Before writing a reply dripping with condescention, why don't you > start by reading the part of the ``manual'' where it says ``always > consistent on disk''? > > Please, lay off the kool-aid, or else drink more of it: Unclean > dismounts are *SUPPORTED*. This is a great supposed ZFS feature BUT > cord-yanking is not supposed to cause loss of the entire filesystem, > not on _any_ modern filesystem such as: UFS, FFS, ext3, xfs, hfs+.
> ... the write barrier problem is pervasive. Linux LVM2 > throws them away, and many OS's that _do_ implement fdatasync() for > the userland including Linux-without-LVM2 only sync part way down, > don't propogate it all the way down the storage stack to the drive, so > file-backed pools (as you might use for testing, backup, or virtual > guests) are not completely safe. > > Aside from these examples, note that, AIUI, Sun's sun4v I/O > virtualizer, VirtualBox software, and iSCSI initiator and target were > all caught guilty of this write barrier problem, too, YES! I recently discovered that VirtualBox apparently defaults to ignoring flushes, which would, if true, introduce a failure mode generally absent from real hardware (and eventually resulting in consistency problems quite unexpected to the user who carefully configured her journaled filesystem or transactional RDBMS!) It seems as though I'll have to dive into the source code to prove it, though: http://forums.virtualbox.org/viewtopic.php?p=59123#59123 There is no substitute for cord-yank tests - many and often. The weird part is, the ZFS design team simulated millions of them. So the full explanation remains to be uncovered? --Toby > so it's not > only, or even mostly, a consumer-grade problem or an other-tent > problem. > ... > The ubifs camp did an end-to-end test for their filesystem's integrity > using a networked power strip to do automated cord-yanking. I think > ZFS needs an easier, faster test though, something everyone can do > before loading data into a pool. > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
