On Tue, Aug 30, 2016 at 5:13 PM, Chris Murphy <li...@colorremedies.com> wrote: > On Tue, Aug 30, 2016 at 4:22 AM, ojab // <o...@ojab.ru> wrote: >> On Mon, Aug 29, 2016 at 9:05 PM, Chris Murphy <li...@colorremedies.com> >> wrote: >>> On Mon, Aug 29, 2016 at 10:04 AM, ojab // <o...@ojab.ru> wrote: >>> What do you get for 'btrfs fi us <mp>' >> >> $ sudo btrfs fi us /mnt/xxx/ >> Overall: >> Device size: 3.64TiB >> Device allocated: 1.82TiB >> Device unallocated: 1.82TiB >> Device missing: 0.00B >> Used: 1.81TiB >> Free (estimated): 1.83TiB (min: 943.55GiB) >> Data ratio: 1.00 >> Metadata ratio: 2.00 >> Global reserve: 512.00MiB (used: 0.00B) >> >> Data,RAID0: Size:1.81TiB, Used:1.80TiB >> /dev/sdb1 928.48GiB >> /dev/sdc1 928.48GiB >> >> Metadata,RAID1: Size:3.00GiB, Used:2.15GiB >> /dev/sdb1 3.00GiB >> /dev/sdc1 3.00GiB >> >> System,RAID1: Size:32.00MiB, Used:176.00KiB >> /dev/sdb1 32.00MiB >> /dev/sdc1 32.00MiB >> >> Unallocated: >> /dev/sdb1 1.01MiB >> /dev/sdc1 1.00MiB >> /dev/sdd1 1.82TiB > > > The confusion is understandable because sdd1 is bigger than sdc1, so > why can't everything on sdc1 be moved to sdd1? Well, dev add > dev del > doesn't really do that, it's going to end up rewriting metadata to > sdb1 also, and there isn't enough space. Yes, there's 800MiB of unused > space in metadata chunks on sdb1 and sdc1, it should be enough (?) but > clearly it wants more than this for whatever reason. You could argue > it's a bug or some suboptimal behavior, but because this is a 99% full > file system, I'm willing to be it's a low priority bug. Because this > is raid0 you really need to add two devices, not just one. > >> I don't quite understand what exactly btrfs is trying to do: I assume >> that block groups should be relocated to the new/empty drive, > > There is a scant chance 'btrfs replace' will work better here. But > still the real problem remains, even if you replace sdc1 with sdd1, > sdb1 is still 99% full which in effect makes the file system 99% full > because it can't do anymore raid0 on sdb1, and it's not possible to do > raid0 chunks on a single sdd1 device. > > If you can't add a 4th drive, you're going to have to convert to > single profile. Keep all three drives attached, 'btrfs balance start > -dconvert=single' and then once that's complete you should be able to > remove /dev/sdc1, although this will take a while because first > conversion will use space on all three drives, and then the removable > of sdc1 will have to copy chunks off before it can be removed. > >> but >> during the delete `btrfs fi us` shows >> Unallocated: >> /dev/sdc1 16.00EiB > > Known bug, also happens when resizing and conversions. > > > >> so deleted partition is counted as maximum possible empty drive and >> blocks are relocated to it instead of new/empty drive? (kernel-4.7.2 & >> btrfs-progs-4.7.1 here) >> Is there any way to see where and why block groups are relocated >> during `delete`? > > The two reasons this isn't working is a.) it's 99% full already and > b.) it's raid0, so merely adding one device isn't sufficient. It's > probably too full even to do a 3 device balance to restripe raid0 > across 3 devices, which is still inefficient because it would leave > 50% of the space on sdd as unusable. To do this with uneven devices > and use all the space, you're going to have to use single profile. > > > > -- > Chris Murphy
Ah, thanks for the elaboration, it makes things much more meaningful now! //wbr ojab -- 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
