So, i use linux with kde and was copying some gigabytes of files from a smartphone to a usb device and while doing that the system monitor kept showing that it was writing some mb/s and i got curious, is said writing happening to my ssd or is it just talking about the usb drive?
The data should be bypassing your internal disk, though depending on the hardware involved it is possible (yet nowadays unlikely) that this will cause swap to be written to the internal disk.
You can watch which device is being written to using iotop.
For files on your phone transferred via MTP, when you open a file directly, it copies it to a temporary folder then you can play the file or open the document, then delete them after you close/disconnect. So transferring files might copy it to the temp folder on your SSD first before moving it.
