On Fri, Aug 26, 2016 at 1:18 PM, Gert Menke <g...@menke.ac> wrote: > Hi Chris, > > first off, thank you for the detailled explanations! > > On 2016-08-26 01:04, Chris Murphy wrote: >> >> No, it's not a file, directory or subvolume specific command. It >> applies to a whole volume. > > You are right, but all I was after in the first place was a way to change > the mode for new data on the whole volume.
New chunks, yes in a rudimentary sense (btrfs balance start then cancel with a dconvert/mconvert), but there's no user control to provide a hint to the allocator which chunks to put new data into. It can go into new chunks or old chunks. Also, I *think* if you cancel the balance, a new balance is not going to complete the conversion - it will do the balance maintaining the mixed profile state of existing chunks. So you'd want to do something like -dconvert=profile,soft -mconvert=profile,soft >> If I add another file, I'll get another data chunk allocated, and >> it'll be added to the chunk tree as item 5, and it'll have its own >> physical offset on each device. > > And this chunk just uses the same profile as the last one (or the parent in > the tree), I suppose. I honestly don't know how it determines what the profile will be; it might be the profile of the chunk with the most recent generation. https://btrfs.wiki.kernel.org/index.php/Compression#Why_does_not_du_report_the_compressed_size.3F > that du will not tell me the compressed size of a file. This is very > counter-intuitive, isn't it? > The reason stated is that some tools apparently determine the sparse-ness of > a file by comparing the size with the stat.st_blocks value. > I do not know if there is a better way to do that, so maybe my argument > falls apart right here, BUT: this looks to me like working around one bug by > introducing another. Wouldn't it be better to have a mount option > "make_du_lie_for_buggy_tools" for those that really need it? BTW, which > tools would an honest du break, and how? (What harm is there in thinking > that a compressed file is sparse?) I don't know anything about this so someone else will have to chime in. -- Chris Murphy -- 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
