On Fri, Jun 10, 2016 at 7:22 PM, Adam Borowski <kilob...@angband.pl> wrote: > On Fri, Jun 10, 2016 at 01:12:42PM -0400, Austin S. Hemmelgarn wrote: >> On 2016-06-10 12:50, Adam Borowski wrote: >> >And, as of coreutils 8.25, the default is no reflink, with "never" not being >> >recognized even as a way to avoid an alias. As far as I remember, this >> >applies to every past version with support for reflinks too. >> > >> Odd, I could have sworn that was an option... >> >> And I do know there was talk at least at one point of adding it and >> switching to reflink=auto by default. > > Yes please! > > It's hard to come with a good reason for not reflinking when it's possible > -- the only one I see is if you have a nocow VM and want to slightly improve > speed at a cost of lots of disk space. And even then, there's cat a >b for > that.
For a nocow VM imagefile, reflink anyhow does not work so cp --reflink=auto would then just duplicate the whole thing, do doing a 'cp --reflink=never' (never works for --sparse), either silently or with a warning/note. For a cow VM imagefile, the only thing I do and want w.r.t. cp is reflink=always, so I also vote for auto on by default. If you want to 'defrag' a VM imagefile, using cat or dd and enough RAM does a better and faster job than cp or btrfs manual defrag. > And the cost on non-btrfs non-unmerged-xfs is a single syscall per file, > that's utterly negligible compared to actually copying the data. > > -- > An imaginary friend squared is a real enemy. > -- > 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 -- 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
