On Sun, Sep 11, 2016 at 09:13:28PM +0200, Martin Steigerwald wrote: > Am Sonntag, 11. September 2016, 16:44:23 CEST schrieb Duncan: > > * Metadata, and thus mixed-bg, defaults to DUP mode on a single-device > > filesystem (except on ssd where I actually still use it myself, and > > recommend it except for ssds that do firmware dedupe). In mixed-mode > > this means two copies of data as well, which halves the usable space. > > > > IOW, when using mixed-mode, which is recommended under a gig, and dup > > replication which is then the single-device default, effective usable > > space is **HALVED**, so 256 MiB btrfs size becomes 128 MiB usable. (!!) > > I don´t get this part. That is just *metadata* being duplicated, not the > actual *data* inside the files. Or am I missing something here? In mixed mode, there's no distinction: Data and metadata both use the same chunks. If those chunks are DUP, then both data and metadata are duplicated, and you get half the space available. Hugo. -- Hugo Mills | Questions are a burden, and answers a prison for hugo@... carfax.org.uk | oneself http://carfax.org.uk/ | PGP: E2AB1DE4 | The Prisoner
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