On Sep 13, 2012, at 1:18 PM, David Lehman wrote: > > Error detection (parity) enables a parity disk AKA RAID4. > > Distributed is really a modifier for the above and enables distributed > parity AKA RAID5. > > Redundant is another modifier that enables redundant distributed parity > AKA RAID6. OK sorry but this is confusing for the following reasons, regardless of whether this is based on md RAID or btrfs RAID. 1.) Wide spread vernacular is "RAID 5 (single parity)" and "RAID 6 (dual parity)". Btrfs's implementation is different from conventional RAID 5, so you could arguably call it "Btrfs single parity (RAID 5)" and "Btrfs dual parity (RAID 6)". But the way it's described now is peculiar, so I suggest the former if this is md RAID, and the latter if it's btrfs RAID. 2.) If this is md RAID, I think it's confusing for it to be in btrfs options, and available for no other file system. 3.) If this is md RAID, RAID 4, 5, 6 do not detect errors at all in normal operation. 4.) If this is btrfs RAID, none of these RAID levels are implemented yet. Btrfs single parity (RAID 5) is supposed to make its way into linux 3.7. But I'm not finding reference for RAID 4 at all, and RAID 6 isn't yet slated for a kernel release. 5.) If this is btrfs RAID, Btrfs always does error detection by default. You'd have to mount with nodatasum or nodatacow at mount time to disable it. Maybe I'm missing something. But it seems to me like punting this down the road to F19 is OK. > Yes, the UI will prevent you from selecting invalid combinations. OK good. [1] RAID 4 as far as I know is not going to be implemented in btrfs. Btrfs RAID 5 is in linux 3.7, and Btrfs RAID 6 isn't slated for a kernel release yet. It could be a while before it is. Chris Murphy _______________________________________________ Anaconda-devel-list mailing list Anaconda-devel-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/anaconda-devel-list
