In <87fwvzuaec....@alamut.ozu.edu.tr>, Volkan YAZICI wrote: >On Tue, 27 Jul 2010, Volkan YAZICI <yazic...@ttmail.com> writes: >> On Tue, 27 Jul 2010, Stan Hoeppner <s...@hardwarefreak.com> writes: >>> What write operations were you performing at the time you pulled the >>> plug? Unless you were writing the superblock it'd be almost impossible >>> to hose the filesystem to the point it couldn't mount. What do you >>> mean, precisely, by "couldn't *recover* the / fs"? >> >> Vanilla XFS with noatime,notail like basic mount options. The test was >> simple, I was just typing "SELECT 1" from a psql command line (this >> query shouldn't even hit to disk, it just basically returns 1) and >> unplugged machine. At boot, I dropped to fsck command line. At command >> prompt, I manually fiddled around with fsck of xfs to recover the >> unmounted / filesystem, but had no luck. (I also tried recommendations >> and informative messages supplied by manpages and command >> outputs/warnings.) > >Another scenario, same failure. >It crashes for some driver specific reasons and >I need to hard-reset the notebook. Now I >lost all of my Opera bookmarks (~500 collected in years). Thanks XFS, >but no, you're not power-failure. (BTW, I "kill -9"ed Opera many times, >and it restored all of its settings properly. I don't think it is an >Opera or WindowMaker related bug.)
XFS is the not only file system where power failure can result in a truncated file. Even ext3 can have that issue, though it is less likely. However, if the application follows a certain procedure when re-writing files, it will not lose data on any of these file systems. I suggest that Opera should be fixed to use that procedure. IIRC, this is a slight variation on the old "two-phase save" that some editors have used for decades, it simply requires a fsync on the temporary file. BTW, a kill -9 is very different from a power failure or a hard reset. In the first case, the application is allowed to do it's own cleanup; the kernel still cleans up after the process -- closing handles to kernel resources, like file descriptors; and queued tasks, like delayed allocation and flushing data to disk, can be run at a later time still. In the later, horrible things happen (e.g. in some systems the HDs and BUS can run for just long enough to complete a DMA transfer AFTER the RAM has lost coherency) and no software gets to run long enough to even detect what is happening, much less put the hardware in a known good state. -- Boyd Stephen Smith Jr. ,= ,-_-. =. b...@iguanasuicide.net ((_/)o o(\_)) ICQ: 514984 YM/AIM: DaTwinkDaddy `-'(. .)`-' http://iguanasuicide.net/ \_/
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