The USB mass storage device class or USB MSC or UMS is a set of computing communications protocols defined by the USB Implementers Forum that run on the Universal Serial Bus. The standard provides an interface to a variety of storage devices.
A USB flash drive like this one will typically implement the USB mass storage device class.
Some of the devices which are connected to computers via this standard are:
* external magnetic hard drives
* external optical drives, including CD and DVD reader and writer drives
* portable flash memory devices
* adapters bridging between standard flash memory cards and a USB connection
* digital cameras
* various digital audio players & portable media players
* Card readers
* Portable Gaming systems (Nokia N-GAGE/Sony PSP)
* personal data assistants and handheld computers
* some newer mobile phones, such as the Sony Ericsson K800 and K510, Nokia N73, Nokia E61http://www.google.com/hostednews/ap/articl...Y-DZZAD96K22L80
Usually, Externals have softwares running through them.
Unless there is a operating system running or an application running on an external hdd then there shouldn't be any activity.
And as for the classification, it places it with the Hard Drives because it technically is a HARD DRIVE. It isn't an Flash Drive, where that is "removable".
A external hdd is a removable device, especially SATAs since they are hot swappable, they have the same protocol for safe removal as other removable USB devices.