Hallo, I''ve added a fourth device (/dev/sdf1; connected via USB) to my 3-disks- btrfs bundle (data raid0, metadata raid1), and then I run "balance". That needed (for about 6 TByte data) about 17 hours. It finished with ERROR: error during balancing ''/srv/MM'' - No space left on device There may be more info in syslog - try dmesg | tail The last lines of "dmesg": btrfs: found 227973 extents btrfs: relocating block group 26872905728 flags 20 btrfs: found 217765 extents btrfs: relocating block group 22577938432 flags 20 usb 1-1: reset high-speed USB device number 3 using ehci-pci usb 1-1: reset high-speed USB device number 3 using ehci-pci usb 1-1: reset high-speed USB device number 3 using ehci-pci usb 1-1: reset high-speed USB device number 3 using ehci-pci usb 1-1: reset high-speed USB device number 3 using ehci-pci usb 1-1: reset high-speed USB device number 3 using ehci-pci usb 1-1: reset high-speed USB device number 3 using ehci-pci btrfs: found 226454 extents btrfs: relocating block group 21504196608 flags 20 btrfs: found 229068 extents btrfs: relocating block group 4324327424 flags 20 btrfs: found 214531 extents btrfs: relocating block group 20971520 flags 18 btrfs: found 92 extents btrfs: relocating block group 4194304 flags 4 btrfs: 1 enospc errors during balance What does the last line mean? Is there 1 error during the 17 hours of balancing? Or has balance ended with "enospc"? The actual state: Commands btrfs fi show df Label: ''MM'' uuid: 7e94022a-76e7-47f8-954d-1ad69a872bef Total devices 4 FS bytes used 6.10TB devid 4 size 1.82TB used 650.03GB path /dev/sdf1 devid 3 size 2.73TB used 1.91TB path /dev/sdd devid 2 size 1.82TB used 1.68TB path /dev/sdc devid 1 size 2.73TB used 1.91TB path /dev/sdb Btrfs Btrfs v0.19 Filesystem 1K-blocks Used Available Use% Mounted on [...] /dev/sdb 9767561292 6554878088 2815565072 70% /srv/MM Viele Gruesse! Helmut -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html