BTRFS has become unmanageable

I'm struggling with a btrfs RAID0 filesystem. It's expanded on 4 disks but i need to remove one of those disks. This is the current status of the filesystem: [root@osgiliath detlev]# btrfs fi show /mnt/Data/ Label: 'Data' uuid: 4c15fe81-ca58-4ac5-adf7-bdde245496f0 Total devices 4 FS bytes used 1.26TiB devid 1 size 2.68TiB used 612.55GiB path /dev/sdc2 devid 2 size 74.53GiB used 74.52GiB path /dev/sda1 devid 3 size 931.51GiB used 606.55GiB path /dev/sdc1 devid 4 size 232.89GiB used 7.52GiB path /dev/sdb and df: [root@osgiliath detlev]# btrfs fi df /mnt/Data/ Data, RAID0: total=1.26TiB, used=1.26TiB System, RAID1: total=32.00MiB, used=112.00KiB Metadata, RAID1: total=3.00GiB, used=1.66GiB GlobalReserve, single: total=512.00MiB, used=143.50MiB I tried deleting /dev/sdc1 but it failed with No space left on device. I tried rebalancing (only metadata first then data also). It balanced some data but now, if I try to delete /dev/sdc1, it moves some (4G) data out of sdc1 to sdb then stops with "No space left on device". If I rebalance, it moves data back from sdb to sdc1. I tried removing sdb too but it just says No space left on device. I am not sure how I can remove that /dev/sdc1 (I know, there are 2 partitions on the same disk, this is due to a broken disk connector, i had to move it temporarily, this is why I want it removed) Any idea ?