Goffredo Baroncelli posted on Tue, 25 Nov 2014 22:59:53 +0100 as excerpted:
> However I still doesn't understood why you want btrfs-w/multiple disk > over LVM ? While I'm not an LVM person here, and he already replied with essentially the same point, I think it's worth repeating... Btrfs' checksummed error detection and automatic rewrite from a different copy isn't a small thing, and simply isn't available at all with most would-be alternatives (zfs being the only similar thing I know of for Linux, and of course it has its own issues both technical and social/ legal/license). That alone is worth running multi-device btrfs to get. That makes btrfs a near-mandatory part of the picture, whatever it's on. And for people wanting LVM's volume management (including partitioning without many of the limitations), the direct result is multi-device btrfs on lvm. >From my perspective, however, btrfs is simply incompatible with lvm snapshots, because the basic assumptions are incompatible. Btrfs assumes UUIDs will be exactly what they say on the label, /unique/, while lvm's snapshot feature directly breaks that uniqueness by copying the (former) UUID, thus making the former UUID no longer unique and thus no longer truly UUID. Thus, part of the lvm /feature/ of snapshots is in direct contradiction to a basic assumption of btrfs, that UUIDs are exactly that, unique, making that feature directly incompatible with btrfs on a very basic level. So people can have their btrfs on lvm, but if they do, they have to forego LVM snapshots because btrfs isn't compatible with their usage. To me it's as simple as that, and people can choose either btrfs or lvm snapshots, but not both, it's one XOR the other. So for me it's simply choose the one you will have the most difficulty doing without and forgo the other one. Not a problem, just make your choice and move on. OTOH, there's that common signature about the reasonable man folding to the circumstance while the unreasonable man insisting on folding the circumstance to his wishes instead, so progress depends on the unreasonable man... But that's exactly what I see here, an unreasonable man insisting that entirely logical circumstance bend to his will. Which, given someone to actually code it up, it might well do. =:^) -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
