While working on an old hard drive, I came across a problem that it would only mount as read only, even when specifying that it should mount as read write. Here’s an example:

mount /dev/sdb1 /media/aptgetlife/datadisk -o remount,rw
mount: cannot remount block device /dev/sdb1 read-write, is write-protected

By this point I’d already got the data disk mounted to the local user media folder, so I could read data from /media/aptgetlife/datadisk but not write data to it.

After some investigation I was able to found this post on stack overflow regarding a similar problem and a solution using blockdev:

blockdev --setrw /dev/sdb1

After which it was possible to run the mount command again, which didn’t present an error and allowed me to write data to the disk.