Hi This is the scenario of data corruption that I was talking about: Mirror has two legs, 0 and 1 and a log. Disk 0 is the default. A write is propagated to both legs. The write fails on leg 0 and succeeds on leg 1. The function "write_callback" puts the bio to "failure" list (if errors_handled was true). It also wakes userspace. do_failures pops the bios from ms->log_failure and calls dm_rh_mark_nosync on them to mark the region nosync. dm_rh_mark_nosync completes the bio with success. *the computer crahes* (before the userspace daemon had a chance to run) On next reboot, disk is 0 revived (suppose that it temporarily failed because of a loose cable, overheating, insufficient power or so, and the condition is repaired), raid1 sees set bit in the dirty bitmap and starts copying data from disk 0 to disk 1. The result: write bio was ended as succes, but the data was lost. For databases, this might have bad consequences - committed transactions being forgotten. - If the above scenario can't happen, pls. describe why. What would be a possible way to fix this? Delay all bios until the userspace code removes the failed mirror? Or store the number of the default mirror in the log? Mikulas -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
