Tech Study Guide
Ceph Storage Examples
Practical Ceph examples for cluster health, replicated pool creation, and RBD image operations.
Ceph Storage Examples
These examples complement Ceph, RADOS, CRUSH, and Placement, and Block, File, and Object Interfaces.
Ceph Examples
Pool creation and health checks:
ceph -s
ceph osd tree
ceph osd pool create app-replicated 128 128 replicated
ceph osd pool set app-replicated size 3
ceph osd pool set app-replicated min_size 2
ceph df
RBD example:
rbd pool init app-replicated
rbd create app-replicated/db-volume --size 102400
rbd info app-replicated/db-volume
rbd snap create app-replicated/db-volume@before-maintenance
Study Cards
Question
Why check ceph -s before changing pools?
Answer
It shows whether the cluster is already degraded, recovering, or blocked before adding more change.
Question
What does pool size 3 mean in a replicated Ceph pool?
Answer
Ceph stores three replicas of each object when placement and health allow it.
Question
Why snapshot an RBD image before maintenance?
Answer
It provides a point-in-time rollback marker for the block image, subject to application consistency.