How to learn Ceph | The reality that NOBODY is telling

“I launch commands but I don’t understand anything”. “I read documentation but when something fails I don’t even know where to start.” “I’ve been with Ceph for a year and I feel like I’m barely scratching the surface.” If any of these phrases resonate with you, you’re not alone. And most importantly: it’s not your fault.

After more than 10 years working with Ceph in production, teaching hundreds of administrators, and rescuing “impossible” clusters at 3AM, we have come to a conclusion that no one will tell you in official certifications: Ceph is brutally difficult to master. And not because you’re a bad administrator, but because the technology is inherently complex, constantly evolving, and the documentation assumes knowledge that no one explicitly taught you.

We’re not going to sell you a “learn Ceph in 30 days”. We want to tell you the truth about how you really learn, how long it takes, what misunderstandings will hold you back, and what is the most effective route to go from blindly throwing commands to having real expertise ;)

Why Ceph is so hard to learn (and it’s not your fault)

Complexity is not accidental: it is inherent

Ceph is not “just another storage system”. It is a massively distributed architecture that must solve simultaneously:

• Write consistency with multi-node replication and distributed consensus
• Continuous availability in the event of hardware failures (disks, nodes, complete racks)
• Automatic rebalancing of petabytes of data with no downtime
• Predictable performance under variable and multi-tenant loads
• Three completely different interfaces (block, object, filesystem) on the same basis
• Integration with multiple ecosystems (OpenStack, Kubernetes, traditional virtualization)

Each of these capabilities separately is a complex system. Ceph integrates them all. And here’s the problem: you can’t understand one without understanding the others.

Documentation assumes knowledge that no one ever taught you

Read any page of the official Ceph documentation and you will find terms like:

• Placement groups (PGs)
• CRUSH algorithm
• BlueStore / FileStore
• Scrubbing and deep-scrubbing
• Peering and recovery
• OSDs up/down vs in/out

The documentation explains what they are, but not why they exist, what problem they solve, or how they interact with each other. It’s like trying to learn to program by starting with the language reference instead of the fundamental concepts.

Constant evolution invalidates knowledge

Ceph changes FAST. And I’m not talking about optional features, but fundamental architectural changes:

• FileStore → BlueStore (2017): Completely changes how you write to disk.
• ceph-deploy → ceph-ansible → cephadm (2020): three different deployment tools in 5 years
• Luminous → Nautilus → Octopus → Pacific → Quincy → Reef → Squid: 7 major versions in 7 years, each with breaking changes.
• Crimson/Seastore (2026+): Complete rewrite of the OSD that will invalidate much of the tuning knowledge.

What you learned 2 years ago about FileStore tuning is completely irrelevant now. The PGs per pool that you were calculating manually are now managed by autoscaler. Networking best practices changed with msgr2.

How long it really takes to master Ceph

Let’s talk with real numbers based on our experience training managers:

Realistic learning progression

Typical misunderstandings that hold back your learning

Misunderstanding #1: “More hardware = more performance”.

I have seen clusters with 40 OSDs performing worse than clusters with 12. Why? Because they had:

• Public network and cluster on the same interface (guaranteed saturation)
• CPU frequency governor in “powersave” (5x degradation in replication)
• PG count totally unbalanced between pools
• BlueStore very low cache for RGW loads

The reality: Ceph performance depends on the weakest link. A single-threaded bottleneck in a MON can bring down the whole cluster. More misconfigured hardware only multiplies the chaos.

Misunderstanding #2: “Erasure coding always saves space”.

A student once proudly said: “I moved my entire cluster to erasure coding 8+3 to save space”. We asked him, “What workload do you have?” – “RBD with frequent snapshots.” Whoops.

Erasure coding with workloads that do small overwrites (RBD, CephFS) is TERRIBLE for performance. And the space “savings” is eaten up with partial stripes and metadata overhead.

The reality: EC is great for object storage cold data (RGW archives). It is terrible for block devices with high IOPS. Knowing the workload before deciding architecture is fundamental.

Misunderstanding #3: “If ceph health says HEALTH_OK, all is well.”

No. HEALTH_OK means that Ceph did not detect problems known to him. It does not detect:

• Progressive disk degradation (SMART warnings)
• Intermittent network packet loss
• Memory leaks in daemons
• Scrubbing that has not been completed for 2 weeks
• PGs with suboptimal placement causing hotspots

The reality: You need external monitoring (Prometheus + Grafana minimum) and review metrics that Ceph does not expose on ceph health. HEALTH_OK is necessary but not sufficient.

Misunderstanding #4: “I read the official doc and that’s enough”.

The official documentation is reference material, not teaching material. Assume you already understand:

• Distributed systems (Paxos, quorum, consensus)
• Storage fundamentals (IOPS vs throughput, latency percentiles)
• Networking (MTU, jumbo frames, TCP tuning)
• Linux internals (cgroups, systemd, kernel parameters)

If you don’t bring that foundation, the doc will confuse you more than help.

The reality: You need additional resources: academic papers on distributed systems, blogs of real experiences, training that connects the dots that the doc omits.

Typical mistakes (that we all make)

Beginner’s mistakes

Intermediate errors

Expert mistakes (yes, we make them too)

The most effective way to learn Ceph

Phase 1: architectural fundamentals (40-60 hours)

Before touching a command, understand:

• What problem does Ceph solve (vs NAS, vs SAN, vs cloud storage)?
• RADOS architecture: how MON, OSD, MGR work
• CRUSH algorithm: why does it exist, what problem does it solve?
• Placement groups: the abstraction that makes the system scalable
• Difference between pools, PGs, objects, and their mapping to OSDs

How to study this: Not with commands, but with diagrams and concepts. A good fundamentals course is 100x more effective than “deploy in 10 minutes” tutorials.

Phase 2: advanced configuration and troubleshooting (60-80 hours)

With solid foundations, you now go deeper:

• BlueStore internals: how the data is actually written
• CRUSH rules customized for complex topologies
• Performance tuning: identifying bottlenecks
• Multi-site RGW for geo-replication
• RBD mirroring for disaster recovery
• Systematic troubleshooting with method

The goal: To move from “I can configure” to “I understand why I configure this way and what trade-offs I am making”.

Phase 3: critical production operations (80-100 hours)

The final leap: from “I know how to configure and troubleshoot” to “I can rescue clusters in production at 3AM”.

• Forensic troubleshooting: diagnosing complex multi-factor failures
• Disaster recovery REAL: recovery of corrupted metadata, lost journals
• Performance engineering: kernel and hardware optimization
• Architectures for specific loads: AI/ML, video streaming, compliance
• Security hardening and compliance (GDPR, HIPAA)
• Scaling to petabytes: problems that only appear on a large scale

The objective: Real verifiable expertise. Eliminate that “respect” (fear) of critical scenarios.

Continuous practice: the non-negotiable ingredient

Here is the inconvenient truth: you can do the 3 courses and still have no expertise if you don’t practice. Theoretical knowledge is forgotten if you don’t apply it.

SIXE’s recommendation after each course:

1. Set up a practice cluster (can be local VMs or cheap cloud).
2. Intentionally breaks things: kills OSDs, fills disks, saturates network
3. Practice recovery without manual: can you recover without Google?
4. Measures everything: benchmarks before/after each change
5. Document your learning: blog, notes, whatever.

Conclusion: the road is long but can be accelerated.

If you made it this far, you are already in the top 10% of Ceph administrators out of pure intent to learn correctly. Most drop out when they realize the real complexity.

The uncomfortable truths you must accept:

1. Mastering Ceph takes 2-3 years of continuous hands-on experience. There are no magic shortcuts.
2. You’re going to make mistakes. Lots of them. Some in production. It’s part of the process.
3. Knowledge depreciates quickly. What you learn today will be partially obsolete in 18 months.
4. Official documentation will never be tutorial-friendly. You need complementary resources.

But there is also good news:

1. Demand for Ceph experts massively exceeds supply. Good time to specialize.
2. You can accelerate the 6-12 month learning curve with structured training that avoids dead ends.
3. Once you “click” on the fundamental architecture, the rest is logically built on that foundation.
4. The community is generally open to help. You are not alone.

Our final advice after 10+ years with Ceph: Start with solid fundamentals, practice constantly, and don’t be afraid to break things in test environments. The best administrators I know are the ones who have broken the most clusters (in labs) and meticulously documented every recovery.

And if you want to significantly accelerate your learning curve, consider structured training that condenses years of practical experience into intensive weeks. Not because it’s easier, but because it saves you the 6 months we all waste attacking problems that someone else has already solved.