Project Description

Obtaining correct information about devices in the system is crucial for multipath-tools. Properties of devices depend on each other. Certain properties matter in some parts of the code and some in others. multipath currently relies strongly on udev, which is good because it provides abstraction, but has also strong drawbacks because udev isn't always reliable and too configurable. In particular during boot, udev lacks information about devices before "coldplug" has been run. Another issue is that some properties are cached in udev and others in sysfs, but for multipathd it's important to obtain up-to-date information.

Goal for this Hackweek

Refactor the way multipathd models physical devices. My (currently vague) idea is to use lazy evaluation of properties, and to model property dependencies explicitly. It sounds weird, but a key factor is to determine reliably whether a given device exists at a given time.