The volume data encountered an error and was made read-only. It is recommended to backup your data.

Was copying data onto my NAS from external hard drives for backup purposes (just had an external drive fail.. so.. I'm a bit paranoid on that right now..). All of a sudden, I couldn't transfer files anymore. Windows said the disk was "write protected" (have the NAS mapped to a drive letter).

Looked at the admin page of the NAS, and it shows it as "healthy". The logs tell a different story:

Nov 08, 2021 03:02:30 PM

Volume: The volume data encountered an error and was made read-only. It is recommended to backup your data.Nov 08, 2021 04:37:10 AM

Volume: Less than 5% of volume data's capacity is free. data's performance is degraded and you risk running out of usable space. To improve performance and stability, you must add capacity or make free space.Nov 07, 2021 11:57:49 PM

Volume: Less than 10% of volume data's capacity is free. data's performance is degraded and you risk running out of usable space. To improve performance and stability, you must add capacity or make free space.Oct 29, 2021 04:27:43 PM

Volume: Less than 20% of volume data's capacity is free. Performance on volume data will degrade if additional capacity is consumed. NETGEAR recommends that you add capacity to avoid performance degradation.

So.. now what?

I'll note I still have 1TB of storage space remaining (at least, that's what's being reported, in Windows and on the admin page..).. but some of the files I thought I had transferred over there appear to have disappeared (specifically, as far as I can tell, the files I transferred towards the end..)