Ceph Use Cases in vSphere: Best Practices, Challenges, and Comparison with vSAN

Davoud Teimouri

10 months ago

Introduction

As data center architectures evolve, the demands on storage systems have never been higher. Traditional storage infrastructures, such as Network-Attached Storage (NAS) and Storage Area Networks (SAN), are facing increasing limitations due to their centralized design, hardware dependency, and scalability concerns. To overcome these challenges, organizations are turning to Software-Defined Storage (SDS) solutions like Ceph and vSAN that provide a more flexible, scalable, and cost-effective approach.

VMware vSphere is one of the main virtualization platforms used today. Despite the close integration of VMware’s proprietary Virtual SAN (vSAN) into the vSphere ecosystem, a growing number of enterprises are choosing open-source storage technologies such as Ceph. The choice to incorporate Ceph into a vSphere system requires knowledge of the architecture’s drawbacks as well as its advantages, use cases, and best practices.

This comprehensive blog post will delve into various use cases for Ceph in a vSphere environment. We will also explore best practices for deployment, the challenges organizations may face and conclude with a comparative analysis between Ceph and vSAN.

What is Ceph?

Ceph is an open-source, software-defined storage platform that provides unified storage, supporting block, file, and object storage. Originally developed by Sage Weil in 2007, Ceph has grown into one of the most popular SDS systems in use today. Ceph’s architecture is built around the concept of distribution, scalability, and fault tolerance, ensuring that no single point of failure can bring down the system.

Ceph consists of several core components:

Monitor (MON): Keeps track of the cluster state, managing the map of the cluster’s state.
OSD Daemon (OSD): Handles data storage, data replication, and recovery. Each OSD typically runs on a physical storage device.
Metadata Server (MDS): Handles the metadata operations for the Ceph file system (CephFS).
Manager (Mgr): Provides cluster monitoring and management functions.

It offers a robust set of storage capabilities such as self-healing, self-managing, and support for massive scalability, making it an attractive option for cloud and data center environments.

Ceph in vSphere: Key Use Cases

The combination of Ceph and vSphere can be a powerful solution for organizations that need flexibility in their storage layer without compromising performance or data integrity. Here are some of the primary use cases where Ceph is used with vSphere:

1. Ceph as Primary Storage for Virtual Machines

Ceph’s block storage (Ceph RBD) is commonly used as the primary storage backend for virtual machine (VM) workloads in vSphere. Each virtual disk is represented as a block device, which can be stored across a Ceph cluster. This use case is popular in cloud infrastructure and private data centers due to the following advantages:

Scalability: Ceph can grow dynamically with your infrastructure. Add more storage nodes to the cluster, and Ceph will automatically redistribute data to ensure load balancing and availability.
Performance: Ceph’s architecture can be optimized for performance by using fast storage like NVMe for frequently accessed data, and slower HDDs for archival or infrequently accessed data.
Resilience: Ceph replicates data across multiple OSDs, ensuring that the failure of individual disks or nodes does not result in data loss.

2. Ceph as a Backup Target for vSphere

Backup and disaster recovery (DR) are critical components of any enterprise IT strategy. Ceph, particularly CephFS or Ceph object storage (S3-compatible), can serve as a highly reliable and cost-effective backup target for VMware environments.

CephFS: This file system can act as a repository for VM backups, snapshots, and other data. With the distributed nature of Ceph, backups are protected against individual hardware failures, ensuring data integrity and availability.
Object Storage: Ceph’s object storage can serve as a highly scalable and resilient target for storing backups, using protocols like S3 or Swift. Backup tools that support these protocols can natively integrate with Ceph for backup operations.

3. Multi-Tenant Private Clouds with OpenStack Integration

For enterprises building private cloud environments using OpenStack on top of vSphere, Ceph provides a unified storage backend. The combination of vSphere for compute virtualization and Ceph for storage allows for a multi-tenant infrastructure where tenants can consume storage on-demand.

Flexibility: Ceph supports block, file, and object storage simultaneously, making it a versatile backend for various OpenStack services (e.g., Cinder for block storage, Glance for image storage, and Swift for object storage).
Isolation: Different tenants can have their own isolated storage pools within Ceph, ensuring secure separation between workloads.

4. Ceph for Big Data and AI/ML Workloads on vSphere

Modern workloads like big data processing, artificial intelligence (AI), and machine learning (ML) require high-performance, scalable storage systems. Ceph’s distributed architecture can efficiently handle the large-scale datasets involved in such workloads when deployed in a vSphere environment.

High Throughput: Ceph’s ability to scale horizontally means that as the data grows, the storage system can grow accordingly without compromising performance.
Flexible Storage Access: Ceph can provide both file and object storage interfaces, making it ideal for AI/ML pipelines that require access to different types of data.

5. Ceph for Compliance and Long-Term Archiving

In industries such as healthcare, finance, and government, strict regulations often mandate long-term data retention and compliance with regulations like HIPAA, GDPR, or SOX. Ceph provides a reliable and scalable solution for archiving data within a vSphere environment.

Cost-Effective Storage: By using different tiers of storage within Ceph, organizations can optimize costs for long-term data retention, using slower, high-capacity HDDs for archival purposes.
Data Integrity: Ceph’s self-healing capabilities ensure that data remains intact over long periods, even as disks fail or undergo maintenance.

Best Practices for Deploying Ceph in vSphere

Deploying Ceph in a vSphere environment requires careful planning and consideration of several factors. Here are some of the best practices to ensure a successful integration:

1. Hardware Considerations

Balanced Node Configurations: Ceph’s performance is highly dependent on the balance between CPU, RAM, network, and storage I/O. Ensure that OSD nodes are equipped with adequate hardware, such as sufficient RAM (recommended 1GB per TB of storage) and appropriate CPU power.
Network Setup: Ceph relies heavily on the network for communication between nodes. Using a dedicated network for Ceph traffic, preferably a high-bandwidth (10Gbps or more) network, is recommended. Jumbo frames should be enabled for better throughput.
NVMe and SSDs: For performance-sensitive workloads, using NVMe drives for OSDs and journal devices can significantly boost performance.

2. Software Configuration

Replication Factor: The default replication factor in Ceph is 3, meaning each piece of data is replicated three times across the cluster. Depending on your use case and hardware availability, this can be adjusted. Keep in mind that lower replication factors may save storage but at the expense of resilience.
Erasure Coding: For capacity-optimized storage, consider using erasure coding instead of replication. Erasure coding provides fault tolerance with less storage overhead, though it may have a performance penalty.
CRUSH Map Tuning: Ceph’s CRUSH map determines how data is distributed across the cluster. Tuning the CRUSH map to account for rack-level or data center-level failure domains can improve fault tolerance.

3. Integration with vSphere

RBD Driver Integration: Ensure that the RBD (RADOS Block Device) driver is correctly configured and optimized for vSphere environments. This includes setting appropriate timeouts, I/O queue depths, and cache settings.
Automation and Monitoring: Tools like Ansible, Terraform, and Ceph’s native management interfaces can automate the deployment and scaling of Ceph clusters in vSphere environments. Monitoring tools like Prometheus and Grafana are essential for proactive management.

Challenges of Using Ceph with vSphere

While Ceph offers numerous advantages, it also comes with challenges that need to be addressed:

1. Complexity of Setup and Management

One of the biggest hurdles for organizations adopting Ceph is the complexity of deploying and managing the cluster. Ceph requires a solid understanding of distributed systems, networking, and storage. Proper planning for failure domains, CRUSH maps, and data distribution strategies can be daunting for those unfamiliar with the platform.

2. Performance Tuning

Ceph performance can vary significantly depending on hardware, network setup, and configuration. Getting the most out of Ceph requires continuous performance tuning and optimization, which can be resource-intensive.

3. Integration and Compatibility

Although Ceph integrates well with vSphere, it is still an open-source product that may not be as seamless or tightly integrated as VMware’s proprietary vSAN solution. Ensuring compatibility between different versions of vSphere, Ceph, and the RBD driver can introduce operational overhead.

4. Storage Efficiency

Ceph’s replication and erasure coding mechanisms provide resilience but at the cost of raw storage efficiency. Organizations must carefully balance their needs for fault tolerance and performance with the overhead of additional storage capacity.

Comparing Ceph and vSAN

Overview of vSAN

VMware vSAN is VMware’s native Software-Defined Storage (SDS) solution that tightly integrates with the vSphere hypervisor, transforming local storage devices within ESXi hosts into a shared, resilient datastore. vSAN is fully integrated with VMware’s suite of products and automates many aspects of storage management, including storage provisioning, policy enforcement, and fault tolerance.

Key characteristics of vSAN include:

Native vSphere Integration: vSAN is built into the VMware hypervisor, eliminating the need for external storage appliances or third-party storage controllers.
Policy-Driven Management: Storage policies dictate how data is stored and protected across the vSAN datastore, enabling administrators to set different performance, availability, and resilience levels based on application needs.
Scalability: As organizations add more ESXi hosts to a vSphere cluster, vSAN can scale storage capacity and performance linearly.

Now, let’s compare Ceph and vSAN across several dimensions to help you choose the right solution for your environment.

1. Integration with vSphere

vSAN: Since vSAN is VMware’s proprietary solution, it is seamlessly integrated with vSphere and ESXi. Tasks such as provisioning storage, setting policies, and monitoring performance are managed directly within the vSphere Client interface. There’s no need to manage a separate storage platform or deal with external drivers.
Ceph: Ceph is not natively integrated into vSphere, which means you need to manage the storage cluster separately from vSphere. While Ceph provides a rich set of APIs and management interfaces, integrating it into vSphere requires configuring Ceph as an external block storage solution via RBD (RADOS Block Device) or NFS. Additional expertise is needed to maintain the cluster alongside vSphere.

Winner: vSAN for native integration and ease of management within vSphere.

2. Flexibility

vSAN: While vSAN is highly optimized for virtualized workloads, it only supports block storage for virtual machines and is restricted to VMware environments. It offers little flexibility in terms of supporting other protocols (e.g., object or file storage) and cannot be used outside of the vSphere ecosystem.
Ceph: Ceph excels in flexibility by supporting block, file, and object storage within a single cluster. It can be integrated into a variety of ecosystems, including Kubernetes, OpenStack, and legacy environments. You can use Ceph for a wide range of workloads beyond vSphere, such as hosting containerized workloads, providing file services, or even acting as a cloud storage backend.

Winner: Ceph for its broader flexibility across different storage types and platforms.

3. Performance

vSAN: vSAN is optimized for vSphere workloads and benefits from being part of the hypervisor. This tight integration means that latency is minimal, and performance can be fine-tuned for specific VM workloads using policies. The performance of vSAN scales as more nodes are added to the cluster, and it can leverage technologies like deduplication and compression to optimize performance further.
Ceph: Ceph’s performance depends heavily on its configuration, hardware, and network setup. While it can be optimized for high performance, especially when using NVMe or SSDs, it may require significant tuning to achieve optimal results. Ceph’s distributed architecture introduces latency, especially when compared to vSAN’s direct integration with the hypervisor. However, Ceph can handle a wide range of workloads beyond just VM storage, including big data and object storage workloads, where its performance is often competitive.

Winner: vSAN for vSphere-optimized performance with minimal latency.

4. Scalability

vSAN: vSAN is highly scalable within the limits of a vSphere cluster. As you add more ESXi hosts to the cluster, vSAN can automatically scale storage capacity and performance. However, scalability is tied to the number of hosts in the vSphere cluster, which may be a limiting factor for very large deployments.
Ceph: Ceph is designed for massive scale-out architectures, capable of handling petabytes of data across hundreds or even thousands of nodes. Its architecture is inherently distributed, and it can scale independently of the compute layer. This makes Ceph ideal for organizations that expect massive data growth and need to scale beyond the constraints of a single vSphere cluster.

Winner: Ceph for its ability to scale to larger environments independently of the compute infrastructure.

5. Ease of Management

vSAN: vSAN is easy to manage, especially for VMware administrators who are already familiar with vSphere. Storage policies are straightforward to configure, and many tasks are automated within the vSphere Client. VMware’s ecosystem provides extensive support, documentation, and tools for managing vSAN.
Ceph: Managing a Ceph cluster requires expertise in distributed storage systems. Ceph’s flexibility and configurability come with a higher management burden, especially in terms of monitoring, maintenance, and performance tuning. That being said, tools like Ceph Dashboard, Prometheus, and Grafana can help monitor and automate some aspects of cluster management, but administrators will need a deeper knowledge base compared to vSAN.

Winner: vSAN for ease of use, especially for organizations already running VMware.

6. Cost

vSAN: vSAN is a licensed product, and costs can vary depending on the size of your environment and the required features (e.g., advanced storage policies, deduplication, and compression). Additionally, you must purchase VMware licenses for your hosts.
Ceph: Ceph is open-source, and the software itself is free to use. However, the total cost of ownership includes the hardware, network infrastructure, and potentially hiring skilled personnel to manage the cluster. Organizations that are comfortable managing open-source software and have the necessary expertise can find Ceph to be a more cost-effective solution, especially at scale.

Winner: Ceph for lower software costs, but vSAN might be more cost-effective for smaller deployments where ease of management offsets the licensing costs.

7. Data Protection and Fault Tolerance

vSAN: vSAN uses storage policies to determine how data is protected across the cluster. This includes settings for fault tolerance (FTT) and RAID levels, ensuring data remains available even if disks or hosts fail. vSAN’s built-in replication and erasure coding provide robust protection against failures within the vSphere cluster.
Ceph: Ceph provides flexible data protection via replication and erasure coding. By default, Ceph replicates data across multiple OSDs and failure domains, ensuring resilience against disk and node failures. Ceph’s CRUSH map allows for highly configurable fault tolerance, enabling administrators to design complex failure domains, such as rack- or data center-level fault tolerance.

Winner: Tie. Both solutions offer robust fault tolerance and data protection mechanisms, though Ceph may provide more granular control over failure domains in larger environments.

8. Use Cases

vSAN: Best suited for organizations that are heavily invested in the VMware ecosystem and primarily run virtual machine workloads. vSAN is ideal for private clouds, VDI environments, and virtualized data centers where ease of management and integration with vSphere is critical.
Ceph: Ceph is well-suited for organizations that need flexible storage solutions beyond just virtual machine workloads. It’s a strong choice for hybrid cloud environments, private cloud deployments with OpenStack or Kubernetes, and use cases that require object and file storage alongside block storage.

Winner: Depends on the use case. vSAN excels for VMware-centric environments, while Ceph provides more versatility across diverse workloads.

Conclusion

Both Ceph and vSAN offer robust, scalable storage solutions, but they cater to different needs. vSAN shines in environments where VMware is the primary platform, providing seamless integration, simplified management, and powerful features tailored to virtualized workloads. Ceph, on the other hand, is a more flexible and open-ended solution, suitable for organizations with diverse storage requirements, massive scalability needs, and expertise in managing distributed storage systems.

Choosing the Right Solution

vSAN: Choose vSAN if you are primarily focused on running vSphere workloads and value tight integration, ease of use, and minimal management complexity. It’s the ideal solution for businesses that want a turnkey storage solution optimized for VMware environments.
Ceph: Choose Ceph if your organization has the expertise to manage distributed systems and requires flexibility across different storage types and platforms. Ceph is the better choice if you plan to scale beyond the limits of a single vSphere cluster or need to support multiple use cases like object storage, file storage, and big data.

External Links

Red Hat Ceph Storage Documentation: https://access.redhat.com/documentation/en-us/red_hat_ceph_storage/4/html/administration_guide/index

VMware vSAN Product Documentation: https://docs.vmware.com/en/VMware-vSAN/index.html

OpenStack and Ceph Integration Whitepapers: https://docs.openstack.org/project-deploy-guide/ceph-ocata/

Ceph Cluster Design and Performance Tuning Guidelines: https://docs.ceph.com/en/latest/start/quick-ceph-cluster/

VMware vSphere Storage Best Practices: https://core.vmware.com/resource/vsphere-storage-best-practices