On 2014-01-09 12:31, Chris Murphy wrote: > > On Jan 9, 2014, at 5:52 AM, Austin S Hemmelgarn > <ahferroin7@xxxxxxxxx> wrote: >> Just a thought, you might consider running btrfs on top of LVM in >> the interim, it isn't quite as efficient as btrfs by itself, but >> it does allow N-way mirroring (and the efficiency is much better >> now that they have switched to RAID1 as the default mirroring >> backend) > > The problem that in case of mismatches, it's ambiguous which are > correct. > At the moment that is correct, I've been planning for some time now to write a patch so that the RAID1 implementation on more than 2 devices checks what the majority of other devices say about the block, and then updates all of them with the majority. Barring a manufacturing defect or firmware bug, any group of three or more disks is statistically very unlikely to have a read error at the same place on each disk until they have accumulated enough bad sectors that they are totally unusable, so this would allow recovery in a non-degraded RAID1 array in most cases. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
