Unexpected SU+J inconsistency AGAIN -- please, don't shift topic to ZFS!

[Lev Serebryakov]

Hello, Ivan.
You wrote 28 февраля 2013 г., 21:01:46:

>>   One time, Kirk say, that delayed writes are Ok for SU until bottom
>>  layer doesn't lie about operation completeness. geom_raid5 could
>>  delay writes (in hope that next writes will combine nicely and allow
>>  not to do read-calculate-write cycle for read alone), but it never
>>  mark BIO complete until it is really completed (layers down to
>>  geom_raid5 returns completion). So, every BIO in wait queue is "in
>>  flight" from GEOM/VFS point of view. Maybe, it is fatal for journal :(
IV> It shouldn't be - it could be a bug.
   I understand, that it proves nothing, but I've tried to repeat
 "previous crash corrupt FS in journal-undetectable way" theory by
 killing virtual system when there is massive writing to
 geom_radi5-based FS (on virtual drives, unfortunately). I've done 15
 tries (as it is manual testing, it takes about 1-1.5 hours total),
 but every time FS was Ok after double-fsck (first with journal and
 last without one). Of course, there was MASSIVE loss of data, as
 timeout and size of cache in geom_raid5 was set very high (sometimes
 FS becomes empty after unpacking 50% of SVN mirror seed, crash and
 check) but FS was consistent every time!


-- 
// Black Lion AKA Lev Serebryakov <lev at FreeBSD.org>