On 27/04/15 14:36, Jean-Baptiste Thomas wrote: > On 2015-04-27 12:54 +0200, David Brown wrote: > >> The problem with all of these is that they /might/ be right - >> but they /might/ be wrong and make matters worse. Even if you >> have 3 copies of the sector, and get two matches and one >> different, there is no way to determine that the odd one is >> wrong. Perhaps a common bus or connector fault caused the >> other two to be wrong. Picking the "majority vote" may >> decrease your chances of losing data (but may not - it depends >> on the cause of the fault), but it certainly does not avoid >> the worst case scenario. > > So Neil's objection is that it's too paranoid and yours is that > it's not paranoid enough ? :-) It's both - it's unlikely to be needed, and in cases where it is needed, it's unlikely to help. Neil has written articles about this before, which are worth reading: <http://neil.brown.name/blog/20110227114201> <http://neil.brown.name/blog/20100211050355> > >> Perhaps the best choice during normal usage (as distinct from >> recovery or rebuild, when the drive is not mounted) is to >> simply report a failure to the layers higher up - that way you >> won't make matters worse by giving returning data. > > You may be right. The main points I think are that > a) the inconsistency be caught and reported and > b) writes be disabled before the propagation of errors buggers > up the whole file system. Yes, that all makes sense. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
