On Sun, Mar 1, 2020 at 5:57 PM Chris Murphy <lists@xxxxxxxxxxxxxxxxx> wrote: > > I'm not following the btrfs logic here - I had three drives, 2 x 1 TB and a 1 x 4 TB and added a 4TB. > > The original three drives: > > devid 2 size 1.82TiB used 1.82TiB path /dev/sda1 > devid 3 size 1.82TiB used 1.82TiB path /dev/sdc1 > devid 4 size 3.64TiB used 3.64TiB path /dev/sdb1 > > Simplistically, devid 2 mirrors with 50% of devid 4, and devid 3 > mirrors with the other 50% of devid 4. You have 4TB of data on an 8TB > volume in a raid1 configuration. That's completely full and using up > all space. > > Then you added one drive. Doesn't matter what its size is. There's no > where for more data to go. > > https://carfax.org.uk/btrfs-usage/ That shows I should have 6TB at RAID1, but only 4TB at RAID10. I'm at RAID1, not RAID10. (Although I'm not sure what the difference is exactly in this context...): $ sudo btrfs fi df /.BACKUPS/ Data, RAID1: total=3.63TiB, used=3.62TiB System, RAID1: total=32.00MiB, used=736.00KiB Metadata, RAID1: total=5.00GiB, used=3.87GiB GlobalReserve, single: total=512.00MiB, used=0.00B The web tool says: Total space for files: 6000 Unusable: 0 Device 2 has size 4000 Device 3 has size 4000 Device 0 has size 2000 Device 1 has size 2000 Allocate 2 chunks at a time Trivial bound is 12000 / 2 = 6000 q=0 bound is 8000 / 1 = 8000
