ceph
How to Add an OSD to Ceph Safely with cephadm
Add a Ceph OSD without wiping the wrong disk: verify health, inventory the device, dry-run an OSD spec, deplo…
Practical guides for planning and running Ceph
CephClusterGuide
Independent · 2026
Independent · 2026
hardware
Ceph Hardware Recommendations for Small Clusters
Ceph hardware recommendations for small clusters: CPU threads and RAM per OSD, PLP SSDs, 10 Gb/s networking, and why N100 boxes fall short.
Read the article →Latest Guides
Storage Comparison
Ceph vs Gluster: Which to Choose for Your Cluster
Compare Ceph and GlusterFS by storage model, workload fit, hardware requirements, cluster size, and support o…
capacity-planning
Ceph Erasure Coding vs Replication: How to Choose
How erasure coding and replication differ in space amplification, failure tolerance and write cost, with a k+…
hardware
Ceph Minimum Hardware Requirements: Nodes, CPU, RAM, Network
Learn why 3 nodes is the Ceph minimum, how many CPU threads and how much RAM each OSD needs, and the drive an…
operations
Ceph HEALTH_WARN: Diagnose and Clear Warnings
A triage order for Ceph HEALTH_WARN covering degraded placement groups, nearfull OSDs, missed deep scrubs, au…
data-placement
Configure a Ceph pool
Understand replica counts and where data is stored before changing pool settings.
Cluster calculator
Raw capacity is not usable capacity
A three-replica pool turns a third of raw storage into usable space. A 4+2 erasure-coded pool turns two thirds of it into usable space, and charges for that in write latency and CPU. The calculator takes an OSD count, a drive size and a redundancy profile, and estimates raw capacity, theoretical usable capacity and the sum of default OSD memory targets.
Open the Ceph erasure coding calculatorExpanding an existing cluster? Follow the guide to add an OSD to Ceph for device checks, a deployment preview and rebalance verification.