Implementing Ceph for Scalable Distributed Storage

Ceph is an open-source distributed storage platform that provides high availability, scalability, and fault tolerance for cloud infrastructures. It supports object, block, and file storage, making it ideal for modern data-intensive applications. This guide focuses on deploying and optimizing Ceph for advanced storage management.

1. What is Ceph?

Ceph is a unified storage system that:

• Scales Horizontally: Add storage nodes to increase capacity.
• Eliminates Single Points of Failure: Distributes data and metadata across clusters.
• Supports Multiple Interfaces: Object storage (S3), block storage (RBD), and shared file systems (CephFS).

2. Ceph Architecture

a) Components

1. Monitor (MON): Maintains cluster state and manages node health.
2. Object Storage Daemons (OSDs): Store data and handle replication.
3. Manager (MGR): Provides additional monitoring and interface functions.
4. Metadata Server (MDS): Manages metadata for the CephFS file system.

b) Data Placement

Ceph uses a CRUSH (Controlled Replication Under Scalable Hashing) algorithm for data placement, ensuring even distribution without a central directory.

3. Setting Up a Ceph Cluster

a) Prerequisites

1. Servers: At least 3 nodes for monitors and additional nodes for OSDs.
2. Network: A reliable, low-latency network.
3. Software Requirements:
   • CentOS, Ubuntu, or similar Linux distributions.
   • Python, ntp, and lvm2 packages.

b) Install Ceph

1. Add the Ceph repository:
   bash

    

   sudo apt update sudo apt install ceph-deploy
2. Create a cluster directory:
   bash

    

   mkdir my-ceph-cluster && cd my-ceph-cluster
3. Deploy monitors:
   bash

    

   ceph-deploy new mon1 mon2 mon3

c) Add OSDs

1. Prepare storage devices on OSD nodes:
   bash

    

   ceph-deploy disk zap osd1:/dev/sdb
2. Add OSDs to the cluster:
   bash

    

   ceph-deploy osd create osd1:/dev/sdb

d) Start the Cluster

Deploy the Ceph configuration:

Verify the cluster status:

4. Ceph Use Cases

a) Object Storage

• Compatible with the S3 API for cloud-native applications.
• Create an object storage pool:
  bash

   

  rados mkpool my-pool
• Access objects using the rados CLI:
  bash

   

  rados put my-object my-data-file --pool=my-pool

b) Block Storage

• Used for VMs, databases, or Kubernetes persistent volumes.
• Map a block device:
  bash

   

  rbd create my-volume --size 1024 rbd map my-volume mkfs.ext4 /dev/rbd0 mount /dev/rbd0 /mnt

c) File System (CephFS)

• Shared file system for HPC or big data workloads.
• Mount CephFS on a client:
  bash

   

  mount -t ceph mon1:/ /mnt -o name=admin,secretfile=/etc/ceph/admin.secret

5. Optimizing Ceph Performance

1. Tune CRUSH Map: Optimize data placement rules based on hardware topology.
2. Enable Journaling: Use SSDs for OSD journals to improve write performance.
3. Use BlueStore: Ceph’s default storage backend offers better performance than FileStore.
   bash

    

   ceph osd set bluestore_compression on
4. Adjust Pool Settings:
   • Use replication for data durability:
     bash

      

     ceph osd pool set my-pool size 3
   • Optimize for read-heavy workloads with erasure coding:
     bash

      

     ceph osd pool create ec-pool 12 erasure

6. Monitoring and Scaling Ceph

a) Monitor Health

Check cluster status regularly:

b) Add Nodes Dynamically

Add a new OSD:

c) Use Dashboards

Enable the Ceph dashboard for real-time metrics:

7. Best Practices for Ceph Deployment

1. Use Dedicated Networks: Separate public and cluster traffic for performance and security.
2. Plan for Redundancy: Use at least 3 monitors and configure data replication.
3. Regular Backups: Periodically back up the Ceph configuration and critical data.
4. Automate Deployments: Use tools like Ansible to automate cluster setup and updates.

8. Common Issues and Troubleshooting

• Slow OSD Performance: Check for hardware bottlenecks and optimize CRUSH maps.
• Cluster in Degraded State: Verify network connectivity and disk health.
• Full Cluster Warning: Adjust quotas or add more OSDs to increase capacity.

Need Assistance?

For advanced Ceph configurations and optimization, contact Cybrohosting’s storage experts. Open a support ticket in your Client Area or email us at support@cybrohosting.com.