On Sat, 3 Jan 2015 13:11:57 +0000 (UTC) Duncan <1i5t5.duncan@xxxxxxx> wrote: > > What about using btrfs on top of MD raid? > > The problem with that is data integrity. mdraid doesn't have it. btrfs > does. Most importantly however, you aren't any worse off with Btrfs on top of MD, than with Btrfs on a single device, or with Ext4/XFS/JFS/etc on top of MD. Sure you don't get checksum-based recovery from partial corruption of a RAID, but you do get other features of Btrfs, such as robust snapshot support, ability to online-resize up and down, compression, and actually, checksum verification: even if it won't be able to recover from a corruption, at least it will warn you of it (and you could recover from backups), while other FSes will pass through the corrupted data silently. So until Btrfs multi-device support is feature-complete (and yes that includes performance-wise), running Btrfs in single-device mode on top of MD RAID is arguably the most optimal way to use Btrfs in a RAID setup. (Personally I am running Btrfs on top of 7x2TB MD RAID6, 3x2TB MD RAID5 and 2x2TB MD RAID1). -- With respect, Roman -- 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
