On 2015-11-20 08:27, Hugo Mills wrote:
On Fri, Nov 20, 2015 at 08:21:31AM -0500, Austin S Hemmelgarn wrote:On 2015-11-20 06:39, Dmitry Katsubo wrote:If I may add:Information for "System" System, DUP: total=32.00MiB, used=16.00KiB is also quite technical, as for end user system = metadata (one can call it "filesystem metadata" perhaps). For simplicity the numbers can be added to "Metadata" thus eliminating that line as well. For those power users who really want to see the tiny details like "System" and "GlobalReserve" I suggest to implement "-v" flag: # btrfs fi usage -vActually, I really like this idea, one of the questions I get asked when I show people BTRFS is the difference between System and Metadata, and it's not always easy to explain to somebody who doesn't have a background in filesystem development. For some reason, people seem to have trouble with the concept that the system tree is an index of the other trees.Actually, it's not that in the system chunks. :) System chunks contain the chunk tree, not the tree of tree roots. They're special (and small) because they're listed explicitly by devid and physical offset at the end of the superblock, and allow the FS to read them first so that it can bootstrap the logical:physical mapping table before it starts reading all the other metadata like the tree of tree roots (which is "normal" metadata).
I guess my understanding was wrong then. Thanks for the explanation.
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