Bug severity is an assessment of customer impact (how bad it will hurt when it happens). But priority is a business decision (informed by severity and release goals) of how important it is to address an issue how soon, and how it should be sequenced relative to other work. The issue priority values used in the Ceph tracker are:
- Immediate … very bad things are happening now.
This problem is so critical that anyone who can possibly help should immediately drop whatever else they are working on, and focus all of their attention on this issue. Examples might be a critical service that is down and cannot be brought back up, or a recent push that has broken the build and has stopped product development or testing. People should not go home if there are “immediate” priority bugs with which they can help.
- Urgent … if we do not fix it very soon, things will quickly get worse.
This is a critical problem (e.g. significant service outage, data loss, performance, or functionality regression) that is so serious that it must be fixed within the current sprint … even if that means abandoning committed development tasks. A (sprintly) release should not be pushed out if it contains “Urgent” priority bugs.
- High … this issue represents a significant exposure in terms of risk or lost opportunity.
This is an important issue, where there will be measurable business consequences if it is not addressed quite soon (e.g. in the next named release). If “High” priority bugs are present in a named release, we need a clear justification for why we believe the release can be successful if this issue is left unresolved.
- Normal … important people are expecting this soon.
This is an issue that should be fixed as soon as possible, but is not so urgent that we must preempt other work. ”Normal” priority bugs may be scheduled to be fixed the next time somebody is working on the related code.
- Low … this is a good idea, but we have considerable latitude in addressing it.
This is a valid, but low impact issue that we should find an opportunity to address, but only after more important issues have been addressed.
Note that all of the resolution is at the high end (where it is most important and a few issues must be tracked carefully). Most bugs are expected to be Normal or Low priority.