While I was trying to find out why the main disk is performing a form of unexpained "thrashing"(while there was no RAM issue), freezing up apps temporarily, I found a relevant error in the logs:
"The driver detected a controller error on \Device\Harddisk1\DR1"
and I'm trying to find which drive it is.
However, from device manager and disk management, the main disk is "0" and there are informational mentions in the logs of dr0 when I enable/disable write caching so it does recognize 0 as different from dr1.
Howevever, the computer has no other disk that I know of and if I open it up while it does have a space for it (laptop), it has no connections for a new one.
I wonder if it's a 'hidden' device of some sort or a problem with the manufacturer's blocking of connections.
In any case I'd like to find out which that device is precisely.
On device manager, DVD drive is mentioned as 'CD ROM 0" when I use 'Populate' in the Volumes tab of its properties and similarly HDD reports disk 0. I still wonder though if for some reason the dvd drive is considered as disk 1 but there's no confirmation of it anywhere. Any other devices such as USB drives etc. are shown as 2, 3, 4 etc. on drive management.
Also looking in HKEY_LOCAL_MACHINE I can only see HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\Scsi\Scsi Port 0\Scsi Bus 0\Target Id 0\Logical Unit Id 0 as PhysicalDrive2 which is a bit weird now that I think of it. That location also confirms the model of the main known drive.
When changing write caching settings \Device\Harddisk0\DR0 is reported on logs (as an information of the change) so \Device\Harddisk0\DR0 is considered by the system different from \Device\Harddisk1\DR1.