[dm-devel] DM-RAID1 data corruption

[Mikulas Patocka]

> > Of course, we can do something in the log itself but it will not fix
> > "corelog" mirrors, more over the system can't auto recover after a
> > missing log alone.
> 
> Yes, storing information on the log device does not save "corelog"
> mirrors, so we might need some area to keep information on mirror
> legs.
> 
> Thanks,
> Taka

MD-RAID1 solves this problem by having counters in superblocks on both 
legs. If some leg dies, the counter on the other devices is increased. If 
the dead disk comes online again, it is found that it has old counter and 
cannot be trusted.

Would it be possible to extend a logical volume when converting it to a 
raid1 and use the last area of the volume as a superblock?

Mikulas