SCSI, Fast SCSI, Ultra SCSI, Ultra2 SCSI: 8 devices
Wide SCSI, Fast Wide SCSI, Ultra Wide SCSI, Wide Ultra2 SCSI, Ultra3 SCSI, Ultra160 and 160+ and Ultra320 : 16 devices
Of course, the number of devices supported depends not only on protocol limitations, but cable length, number of cables used, etc.
8
Most modern SCSI buses support a total of 16 devices, while older SCSI implementations usually support only eight devices.
Wide SCSI bus can support up to 16 devices using channels 0-15.
16 devices can be connected
8 Devices can be used on a single SCSI bus.
Scsi has nothing to do with disk partition.
7
127
Depends on what the SCSI is. Ultra? Ultra Wide? Ultra Wide 2? many different types.
usb 2.0 can support 127 devices
In it's day, SCSI was a great, high-speed disk interface. Today, IDE has pretty much taken over and SCSI isn't really worth the effort that it takes to support it. However, SCSI does have an option for an external connection. USB is an acronym for Universal Serial Bus and it's a great way to interconnect devices with your computer. Each USB device is SUPPOSED to have a built in identification code that allows the computer to identify what it's talking to. Drivers are available, either built in to Windows, Apple or Linux systems, downloadable across the internet or included with the device when you buy it. Most USB devices are truly "universal".
I am assuming you mean what is SCSI used for? In this case, SCSI does NOT mean "small computer serial interface," instead, it means "Small Computer SYSTEM Interface." SCSI is used as a fast interface between a host adapter and the CPU that can daisy chain as many as 7 or 15 devices on a single bus.