My laptop’s HDD is failing, it shows a bunch of signs such as slow file manipulation and clicking sounds. The Linux btrfs partition keeps going into read-only mode to prevent further damage, makes sense, but the windows partition is working fine (for now).
Shouldn’t harddrive failure be evident on all partitions?
It depends on the exact nature of the failure. Controller errors are usually a complete failure. Media failure (magnetic spots on the disk or failed cells in ssd) are often sporadic and only impact data stored in those spots.
Regardless, drives rarely give you any warning. Look at any warning as a gift and get everything off and replace it ASAP.