That’s… A lot of storage. I’d say your options are, in no particular order:
buy a 12 bay NAS.
expansion unit. Do it as a separate volume and shuffle cold data onto there.
upgrade the drives.
Failing that you could just have a bit of a purge? If not straight deleting stuff, move things onto an external drive.
You could also try deduping. There’s a script that’ll add any drive to the internal “supported” list and also enable dedupe on mechanical drives. The savings were minimal on mine but you might have more luck. https://github.com/007revad/Synology_enable_Deduplication
That’s… A lot of storage. I’d say your options are, in no particular order:
Failing that you could just have a bit of a purge? If not straight deleting stuff, move things onto an external drive.
You could also try deduping. There’s a script that’ll add any drive to the internal “supported” list and also enable dedupe on mechanical drives. The savings were minimal on mine but you might have more luck. https://github.com/007revad/Synology_enable_Deduplication