4.2 Disk Device Files in a Switched Fabric, Fibre Channel SAN
4.3 Online Addition and Replacement: OLA/R
Before we can use a device, we need to create a device file for it. This harkens back to the notion that "everything in UNIX is a file." Some devices will format the data stored on it; a filesystem formats the data for ease of management and better performance when reading and writing. Whether the data is formatted or not, the device file concept makes communicating with devices very simple; open the device file, and start reading or writing. Being a CSA, you will be familiar with concepts such as hardware paths and the ioscan command. We look at some situations where communicating with peripherals is a little more involved; we will look at restructuring our IO tree using ioinit ; we discuss how a switched fabric, fibre channel SAN affects the device files for disks; and we will conclude by looking at OLA/R, the ability to replace a PCI interface card while the system is still running.
