ReadyNAS 104 - Out of Disc Space, but showing 6.3T

[Geoff8386]

Hi - I use this NAS purely for backups it has 4 x 4TB drives in it.    Windows Server can access it fine and says I have 6.3T Free however when I try and write anything to it, it says disc space is full.  I've checked my snapshots and I have none enabled.     If I delete something additionally to increase the space it will does allow me to then save and then comes up with the usage disc space full.

Has anyone got any ideas on how to sort this, as I don't really want to go back to factory settings and start again even through it is a backup... 

Thanks

I've on firmware 6.5.2 and using RAID-X    - I've done a balance and defrag and now doing a scrub - however taking a while on 12% at the moment

I've ssh into system and done a df -h

Filesystem      Size  Used Avail Use% Mounted on
udev             10M  4.0K   10M   1% /dev
/dev/md0        3.7G  449M  3.1G  13% /
tmpfs           249M     0  249M   0% /dev/shm
tmpfs           249M   14M  236M   6% /run
tmpfs           249M     0  249M   0% /sys/fs/cgroup
tmpfs           249M     0  249M   0% /media
/dev/md127       11T  4.7T  6.3T  43% /data
/dev/md127       11T  4.7T  6.3T  43% /apps
/dev/md127       11T  4.7T  6.3T  43% /home
/dev/md127       11T  4.7T  6.3T  43% /run/nfs4/home

[mdgm-ntgr]

Can you send me your logs (see the Sending Logs link in my sig)?