On Thu, 6 Feb 2014 22:30:46 -0700 Chris Murphy <li...@colorremedies.com> wrote:
> >From the original post, context is a 2x 1TB raid volume: > > Filesystem Size Used Avail Use% Mounted on > /dev/sda2 1.8T 1.1M 1.8T 1% /mnt/p2 > > Earlier conventions would have stated Size ~900GB, and Avail ~900GB. But > that's not exactly true either, is it? Much better, and matching the user expectations of how RAID1 should behave, without a major "gotcha" blowing up into their face the first minute they are trying it out. In fact next step that I planned would be finding how to adjust also Size and Used on all my machines to show what you just mentioned. I get it that btrfs is special and its RAID1 is not the usual RAID1 either, but that's not a good reason to break the 'df' behavior; do whatever you want with in 'btrfs fi df', but if I'm not mistaken the UNIX 'df' always was about user data, how much of my data I have already stored on this partition and how much more can I store. If that's not possible to tell, then try to be reasonably close to the truth, not deliberately off by 2x. > On Btrfs ...the amount Avail is likewise not wrong because that space is "not > otherwise occupied" which is the definition of available. That's not the definition of available that's directly useful to anyone, but rather a filesystem-designer level implementation detail, if anything. What usually interests me is, I have a 100 GB file, can I fit it on this filesystem, yes/no? Sure let's find out, just check 'df'. Oh wait, not so fast let's remember was this btrfs? Is that the one with RAID1 or not?... And what if I am accessing that partition on a server via a network CIFS/NFS share and don't even *have a way to find out* any of that. -- With respect, Roman
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