Introduction
Block storage and local disk are two of the most common storage options used in cloud infrastructure. While both store application data, they serve very different purposes in terms of performance, durability, and flexibility.
Understanding the difference between these storage models is essential when designing reliable systems. Choosing the wrong storage type can lead to performance bottlenecks, complicated migrations, or unexpected data loss during server replacements.
In this guide, you will learn how block storage and local disk work, when to use each option, and how modern cloud infrastructure platforms like Raff allow you to combine both approaches to build reliable and scalable systems.
Understanding Local Disk Storage
Local disk storage refers to storage that is physically attached to the server running your virtual machine. In cloud environments, this storage is usually backed by high-speed NVMe solid-state drives.
Because the storage is directly connected to the server hardware, local disk provides very fast read and write performance.
Typical characteristics of local disk storage include:
- Very low latency
- High read and write throughput
- Storage tied to a specific virtual machine
- Limited portability between servers
Local disk is often used for workloads where raw performance matters more than portability.
Examples include:
| Use Case | Why Local Disk Works Well |
|---|---|
| Temporary data processing | Fast local writes |
| Application caching | High-speed access |
| Build systems and CI pipelines | Short-lived workloads |
| Log storage | High write throughput |
However, local storage also comes with a limitation: it is usually tied to the lifecycle of the virtual machine. If the server is deleted or replaced, the local disk may be lost.
For workloads where persistence is critical, other storage options are often more appropriate.
Understanding Block Storage
Block storage is a persistent storage service that allows disks to exist independently from a specific virtual machine. Instead of being tied to a server, block storage volumes can be attached or detached from different machines.
From the operating system’s perspective, block storage behaves like a normal disk device.
Common features of block storage include:
- Persistent storage independent of the VM lifecycle
- Ability to attach volumes to servers
- Storage expansion without replacing servers
- Compatibility with standard file systems
Because block storage exists independently, it is typically used for data that must survive server replacement or scaling operations.
Typical use cases include:
| Use Case | Why Block Storage Is Preferred |
|---|---|
| Databases | Data must persist independently of servers |
| File uploads | Application storage must survive deployments |
| Backups | Separate storage improves recovery options |
| Shared application data | Volumes can move between instances |
This flexibility makes block storage one of the most important components of modern cloud architecture.
Key Differences Between Block Storage and Local Disk
Although both storage models can hold application data, they serve different architectural roles.
| Feature | Local Disk | Block Storage |
|---|---|---|
| Location | Attached to VM | Independent storage volume |
| Performance | Very high | High but network-based |
| Persistence | Often tied to VM | Persistent across servers |
| Flexibility | Limited | Highly flexible |
| Scalability | Requires VM resizing | Volumes can expand independently |
Local disk prioritizes speed, while block storage prioritizes durability and flexibility.
The correct choice depends on the workload.
Performance Considerations
Performance is one of the most common reasons developers choose local storage. Since NVMe disks are attached directly to the server hardware, they deliver extremely low latency.
Block storage introduces a small amount of network overhead because storage traffic moves between the server and the storage system.
However, modern cloud block storage systems are still very fast and suitable for most production workloads, including databases and application storage.
A useful rule of thumb is:
- Use local NVMe storage when you need maximum performance.
- Use block storage when you need persistence and flexibility.
Many architectures combine both approaches.
For example:
| Component | Storage Type |
|---|---|
| Application cache | Local disk |
| Application uploads | Block storage |
| Database storage | Block storage |
| Temporary processing files | Local disk |
This hybrid model allows systems to benefit from both performance and durability.
Storage Architecture Best Practices
When designing infrastructure, storage should not be an afterthought. The location of your data determines how easy it is to scale, migrate, or recover systems.
Several best practices are commonly recommended.
Separate Compute and Persistent Storage
Applications should ideally be stateless, meaning they can run on any server without depending on local disk data.
Persistent data such as uploads or databases should live on dedicated storage volumes.
This separation allows you to:
- Replace servers without losing data
- Scale compute resources independently
- Move workloads across infrastructure
Use Block Storage for Critical Data
Critical application data should not depend entirely on the lifecycle of a single server.
Block storage provides persistent volumes that remain available even if the server is replaced or upgraded.
This makes it well suited for:
- Databases
- Application files
- Long-term logs
- Backup repositories
Combine Storage with Backup Strategies
Storage durability and backup strategies work together.
Even persistent volumes can fail due to accidental deletion, software bugs, or security incidents.
For this reason, cloud architectures typically combine:
- Block storage volumes
- Scheduled backups
- Snapshots before major changes
This layered approach improves reliability and disaster recovery readiness.
Block Storage on Raff
Raff Technologies provides block storage volumes that can be attached to virtual machines to expand storage capacity beyond the base disk included with each server.
These volumes behave like additional disks that can store application data, databases, and backups.
Developers commonly use Raff volumes for:
- Database storage
- File uploads and media storage
- Backup repositories
- Shared application data
Since Raff volumes are independent resources, they allow infrastructure to scale without forcing server replacement when storage needs grow.
Combined with Raff snapshots and automated backups, block storage helps teams build reliable systems that can recover from failures or configuration mistakes.
Conclusion
Choosing the right storage model is an important part of cloud infrastructure design. Local disk provides extremely fast storage tied directly to the server, making it ideal for temporary workloads and caching.
Block storage provides persistent volumes that remain independent of server lifecycles, making it better suited for databases, backups, and long-term application data.
Most production architectures combine both approaches: local storage for performance-sensitive temporary data and block storage for persistent workloads.
Platforms like Raff make it easy to combine these strategies by offering high-performance NVMe virtual machines alongside flexible block storage volumes, allowing teams to design infrastructure that balances speed, reliability, and scalability.