Back to: Storage Area Network (SAN) Storage
Here’s an overview of Thin and Thick Provisioning in storage, along with some images to illustrate the concept.
Storage Provisioning: Thin vs. Thick
Storage provisioning refers to allocating storage capacity to applications or virtual machines (VMs) based on predefined policies. There are two primary methods:
- Thick Provisioning (Pre-Allocated)
- Thin Provisioning (On-Demand Allocation)
1. Thick Provisioning (Pre-Allocated)
Thick provisioning reserves the entire storage capacity at the time of allocation, whether it is used or not.
Characteristics:
- The full storage space is allocated immediately.
- Ensures predictable performance.
- Prevents over-subscription issues.
- Can lead to unused or wasted storage space.
Example: If a VM is allocated 100GB, the full 100GB is immediately reserved, even if only 10GB is used.
2. Thin Provisioning (On-Demand Allocation)
Thin provisioning allocates storage dynamically as data is written, instead of reserving the entire space upfront.
Characteristics:
- Allocates only the storage required at any given time.
- Enables over-provisioning (more virtual storage than physical storage).
- Can lead to performance issues if the physical storage runs out.
- Requires careful monitoring.
Example: If a VM is allocated 100GB, but only 10GB is used, only 10GB of actual storage is consumed, with more allocated as needed.
Key Differences:
| Feature | Thick Provisioning | Thin Provisioning |
|---|---|---|
| Storage Allocation | Full upfront | As needed |
| Performance | More predictable | May degrade if over-subscribed |
| Efficiency | Can waste unused space | Maximizes storage utilization |
| Over-Provisioning | Not possible | Possible but risky |
When to Use What?
- Thick Provisioning: Best for performance-sensitive workloads like databases.
- Thin Provisioning: Ideal for environments with unpredictable growth, such as cloud and virtualized environments.