Lost objects and inactive PGs

This section of the chapter will cover the scenario where a number of OSDs may have gone offline in a short period of time, leaving some objects with no valid replica copies. It's important to note that there is a difference between an object that has no remaining copies and an object that has a remaining copy, but it is known that another copy has had more recent writes. The latter is normally seen when running the cluster with min_size set to 1.

To demonstrate how to recover an object that has an out-of-date copy of data, let's perform a series of steps to break the cluster:

  1. First, let's set min_size to 1; hopefully, by the end of this example, you will see why you don't ever want to do this in real life: ...

Get Ceph: Designing and Implementing Scalable Storage Systems now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.