Hugo Mills posted on Wed, 03 Sep 2014 08:33:05 +0100 as excerpted: > On Wed, Sep 03, 2014 at 04:53:39AM +0000, Duncan wrote: >> Hugo Mills posted on Tue, 02 Sep 2014 13:13:49 +0100 as excerpted: >> >> >> [A] btrfs fi df on a new filesystem always seems to have those extra >> unused single profile lines. >> >> I got so the first thing I'd do on first mount was a balance -- before >> there was anything actually on the filesystem so it was real fast -- to >> get rid of those null entries. > > Interesting. Last time I tried that (balance without any contents), > the balance removed *all* the chunks, and then the FS forgot about what > configuration it should have and reverted to RAID-1/single. I usually > recommend writing at least one 4k+ file to the FS first, if it's > bothering someone so much that they can't let it go. Interesting indeed. From memory, even before I've put anything on the filesystem it always seems to have a bit of the first chunk of both data and metadata used -- not much but enough that it's obvious in the df which mode chunks are the null-chunks, and apparently obvious to the balance as well, as it has always left me with at least a first chunk of each. I wonder what the difference might be. Perhaps it's just the versions of kernel and/or userspace I've happened to do all my mkfs.btrfs with? Or maybe it's one of the features (like thin-metadata or noholes) I enable by default, or the fact that I use labels for partition ID and tracking, so I always fill that in. Whatever it is, it seems to put a bit of something in the filesystem, possibly at first mount, so the actually used chunks, one each of data and metadata, aren't entirely empty. Or maybe I'm remembering wrong and I've just been lucky. <shrug> -- 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 majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
