On Sun, Sep 11, 2016 at 8:00 PM, Duncan <1i5t5.dun...@cox.net> wrote: > Chris Murphy posted on Sun, 11 Sep 2016 14:33:18 -0600 as excerpted: > >> Something else that's screwy in that bug that I just realized, why is it >> not defaulting to mixed-block groups on a 100MiB fallocated file? I >> thought mixed-bg was the default below a certain size like 2GiB or >> whatever? > > You apparently missed the memo...
I got the memo right after I clicked send and read the thread. > Newer btrfs-progs mkfs.btrfs no longer defaults under-1-GiB to mixed-bg > mode, tho it remains very strongly recommended below 1 GiB, and soft- > recommended to somewhere between 4 and 32 GiB (I believe the wiki says 5 > GiB at this point but don't know how it arrived at that, but the numbers > I've seen suggested on-list range between 4 and 32 GiB, as above). > > The explanation of why, based on the thread where I remember it coming > up, was because defaulting to mixed-mode was making testing more > complex. Don't ask me to agree with that because I most certainly don't; > IMO sane defaults for normal use, which everyone seems to agree mixed- > mode for under a GiB is, should apply, and if testing needs special- > cased, well, special-case it. But none-the-less, that's the context in > which it was agreed to do away with the mixed-mode default, despite it > still being extremely strongly recommended for under a GiB. <shrug> The man page says: "The recommended size for the mixed mode is for filesystems less than 1GiB." But in this case recommended !=default which requires some mental gymnastics to rectify. If mixed-bg becomes obsolete upon enospc being no more likely with isolated block groups, then OK fine, but in the meantime... -- 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
