Benchmarking

There are utilities built into Ceph to measure performance, as well as valuable external tools. We'll discuss both. It's important to remember that workloads that issue smaller requests will yield much lower numbers than those issuing larger requests.

RADOS bench

To use Ceph's built-in tool, first create a dedicated, disposable pool to scribble into. For this to be a legitimate test, it must have the same attributes as your production pool: PG count, replication factor, CRUSH rules, etc.

Options to rados bench include:

• -p: The name of our dedicated test pool
• seconds: Number of seconds the test should run
• write|seq|rand: Type of workload to present: write, sequential read, random read
• -t: Number of concurrent operations; the default is 16
• --no-cleanup: Don't clean up the objects created during the run

Let's run a 60 second write test against a small cluster with a pool named data. A dedicated pool should be used to ensure that user data is not clobbered. Longer tests are better than shorter...