Hi, thanks for the answer. I've still some comments on the topic, see below. > Suppose we agree that bit flips don't happen (undetected) on drive > media. But that bit flips can happen elsewhere (memory. IO Buss > etc). > > And then suppose we discover that a bit-flip has happened. What does > that tell us? > Maybe it tells us that our hardware is dodgey. So it cannot be > trusted to reliably do anything we tell it. So maybe we shouldn't > tell it to do anything. ?? Maybe I should try to clarify the concept. There are *two* use cases. One is the "check" and one is the "repair". As I already wrote, I do agree that "repair" needs some deeper thinking. It is easy to see cases where it could produce more damages. The "check" case is another story. In case of RAID-6 I would like, as RFE, to have in the logs some report on which "drive" or "data path" the mismatch occurs, when detectable. So, if the mismatch count says there are 1024 mismatches, then would be nice to know if they belong all to the same drive or not. In this case, it would be possible to fail/remove that one and check the hardware (change drive/cable/connector/etc.). Ideally, at the end of the "check", the log should report how many mismatches, how many are "undeterminable" (multiple drive), how many could belong to a specific drive. This will help to to diagnose a problem, maybe reported by the CRC in the filesystem. This is for the "check", about the "repair", the only possible change I could see is to offer the user, and we could check in this mailing list how many would like to have the possibility, the option to "reset the parity" of the array or "recalculate the data", with the warning that the second one can do more damage than already has. Conclusion, for me, is that the "check" should be more clever, with RAID-6, and "repair/resync" *might* be more flexible (with warnings). I take the opportunity to wish you all Merry Christmas and Happy New Year. bye, -- pg Jetzt komfortabel bei Arcor-Digital TV einsteigen: Mehr Happy Ends, mehr Herzschmerz, mehr Fernsehen! Erleben Sie 50 digitale TV Programme und optional 60 Pay TV Sender, einen elektronischen Programmführer mit Movie Star Bewertungen von TV Movie. Außerdem, aktuelle Filmhits und spannende Dokus in der Arcor-Videothek. Infos unter www.arcor.de/tv -- 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
