2.8 Peripherals

In this section, we discuss most of the miscellaneous ports that haven't been discussed in preceding sections. We give only a cursory description because these components aren't generally used in cluster configurations.

USB and Firewire are peripheral buses. Devices can be connected into these buses. The bus controller bridges the devices onto the primary I/O bus (in most cases, some flavor of PCI) so that the devices can be used. USB keyboards and mice are common; other than these two cases, it is unlikely that any USB or firewire devices will be used in these systems. Generally, devices of these types are consumer electronics, such as cameras, printers, and handheld devices.

The other major group of peripherals is quite old; all have been included in all PCs sold in the last 15 years. Included in this group are dedicated keyboard and mouse ports. These are typically used to debug problems, as setting up a keyboard and mouse for every node in a cluster isn't a particularly space-efficient decision to make. Also, all machines have serial (RS232) and parallel ports. These were historically used for peripherals, much like USB and firewire; however, in modern clusters, RS232 is used for a hard-wired system console, and parallel ports aren't used at all.

Since these devices have little to no bearing on cluster manageability or performance, they don't enter into any decisions in the node hardware specification process. If a choice is offered between nodes with 2 or 6 USB ports it doesn't matter which is chosen.