Painfully slow rebalance/RAID conversion

btrfs fi show /mnt2/main_pool shows

Label: ‘main_pool’ uuid: 07f188d4-44d6-49fd-86ac-0380734fe1d2
Total devices 8 FS bytes used 12.09TiB
devid 2 size 1.82TiB used 1.82TiB path /dev/sdg
devid 5 size 1.82TiB used 1.82TiB path /dev/sde
devid 7 size 5.46TiB used 2.13TiB path /dev/sdh
devid 8 size 5.46TiB used 2.13TiB path /dev/sdf
devid 9 size 7.28TiB used 2.13TiB path /dev/sdc
devid 10 size 7.28TiB used 2.13TiB path /dev/sdd
devid 11 size 7.28TiB used 2.78TiB path /dev/sdb
devid 12 size 7.28TiB used 2.78TiB path /dev/sda

The UPS I have is a CyberPower 1325VA. I don’t recall having to do anything special to get it working. I used to get emails every week or two about power fluctuations so I’m assuming that it is working well.
However, I haven’t bothered to set up email since I reinstalled Rockstor a while back. I need to get on that.

Edit: You asked for usage, not show

btrfs fi usage /mnt2/main_pool
WARNING: RAID56 detected, not implemented
WARNING: RAID56 detected, not implemented
Overall:
Device size: 43.66TiB
Device allocated: 6.06GiB
Device unallocated: 43.66TiB
Device missing: 0.00B
Used: 331.44MiB
Free (estimated): 0.00B (min: 8.00EiB)
Data ratio: 0.00
Metadata ratio: 0.30
Global reserve: 512.00MiB (used: 0.00B)

Data,RAID6: Size:12.13TiB, Used:12.07TiB
/dev/sda 2.78TiB
/dev/sdb 2.78TiB
/dev/sdc 2.12TiB
/dev/sdd 2.12TiB
/dev/sde 1.82TiB
/dev/sdf 2.12TiB
/dev/sdg 1.82TiB
/dev/sdh 2.12TiB

Metadata,RAID1: Size:3.00GiB, Used:164.83MiB
/dev/sdc 3.00GiB
/dev/sdd 3.00GiB

Metadata,RAID6: Size:17.09GiB, Used:15.00GiB
/dev/sda 4.85GiB
/dev/sdb 4.85GiB
/dev/sdc 4.10GiB
/dev/sdd 4.10GiB
/dev/sde 612.31MiB
/dev/sdf 3.85GiB
/dev/sdg 612.31MiB
/dev/sdh 3.85GiB

System,RAID1: Size:32.00MiB, Used:912.00KiB
/dev/sdc 32.00MiB
/dev/sdd 32.00MiB

Unallocated:
/dev/sda 4.50TiB
/dev/sdb 4.50TiB
/dev/sdc 5.15TiB
/dev/sdd 5.15TiB
/dev/sde 1.17GiB
/dev/sdf 3.33TiB
/dev/sdg 1.17GiB
/dev/sdh 3.33TiB