Let’s compare Exadata Database Service on Exascale Infrastructure (ExaDB-XS) and Exadata Database Service on Dedicated Infrastructure (ExaDB-D) and review how to choose between these services. Both Oracle Database services run on powerful Exadata hardware within the Oracle Cloud Infrastructure (OCI) public cloud, but they differ in their underlying infrastructure model and characteristics.
- Exadata Database Service on Dedicated Infrastructure (ExaDB-D):
- Runs your Oracle databases on dedicated Exadata database servers and storage servers physically allocated solely to you within an OCI region. Think of it as single-tenant at the hardware infrastructure level, providing maximum isolation in the public cloud. You start with two database nodes and three storage servers.
- Exadata Database Service on Exascale Infrastructure (ExaDB-XS):
- Runs your Oracle databases on the shared infrastructure of Exadata compute and storage resources within OCI. Exascale architecture decouples compute and storage for greater flexibility and elasticity. Consider it multi-tenant at the hardware infrastructure level, though your VMs provide logical isolation. Instead of dedicated database servers and storage, you get a dedicated Exadata cluster with dedicated CPU and Storage.
2. Key Differences and Decision Points:
| Feature | ExaDB-XS | ExaDB-D | Decision Driver |
|---|---|---|---|
| Infrastructure | Shared, multi-tenant pools of Exadata compute & Exascale storage | Dedicated, physically isolated Exadata compute & storage servers | Isolation: Choose D for maximum physical isolation. XS offers VM-level isolation on shared hardware. |
| Isolation | Logical isolation via VM clusters on shared hardware | Physical isolation with dedicated servers | Compliance/Security: D meets stricter requirements for physical separation. |
| Scalability | Hyper-elastic; fine-grained scaling of ECPUs & Exascale Vault storage | Scales ECPUs/OCPUs dynamically; infrastructure scales by adding dedicated servers | Elasticity: XS offers more granular scaling, especially for storage, and potentially faster VM provisioning. |
| Minimum Size | Low entry point (starts with 8 ECPUs, 300 GB storage) | Higher entry point (requires minimum server configuration, 2 DB Servers + 3 Storage Servers) | Cost/Starting Small: XS is more cost-effective for smaller workloads or starting new projects. |
| Cost Model | Generally lower entry cost; pay-per-use compute & storage | Higher entry cost for infrastructure; pay-per-use compute | Budget: XS provides Exadata power at a potentially lower cost, especially initially. |
| Performance | High Exadata performance on shared infra; benefits from Exascale arch. | Predictable high Exadata performance on dedicated resources | Predictability: D offers the most predictable performance baseline, free from potential “noisy neighbors”. |
| Storage Management | Abstracted via Exascale Vault; simplified scaling | Managed via ASM across dedicated storage servers | Simplicity: XS simplifies storage management (no need to manage ASM allocation across servers). |
| Maintenance | Underlying host maintenance may require scheduled VM restart/migration | Maintenance scheduled for the dedicated system | Control: D may offer more perceived control over infrastructure maintenance windows (though both managed by Oracle). |
| Key Features | Exascale architecture (direct I/O, RDMA), efficient thin cloning. Supports DB 23ai. | Established platform, supports DB versions 19c and 23ai. | Specific Needs: XS is ideal for leveraging efficient clones. Check DB version support for XS if not using 23ai. |
| VM Portability | High; VM filesystems on shared storage enable easier migration | Lower; VM filesystems traditionally tied more closely to local compute resources | Flexibility: XS architecture facilitates easier movement of VMs across underlying physical hardware. |
3. When to Choose ExaDB-XS (Exascale Infrastructure):
- Cost Sensitivity: You need the power of Exadata but require a lower entry cost than dedicated hardware. Consolidate various smaller databases that demand high performance.
- Elasticity is Key: Your workload is variable or unpredictable, and you need the ability to scale computing resources up or down quickly and granularly.
- Starting Small: You are deploying a new application or migrating smaller workloads and want to start with a minimal footprint and grow later.
- Development & Testing: You need to rapidly provision/de-provision environments and leverage efficient database cloning (thin clones) for multiple developers or test cycles.
- Simplified Storage Management: You prefer an abstracted storage layer (Exascale Vault) that does not require managing ASM allocations across specific storage servers.
- Physical Isolation Not Mandatory: Logical isolation provided by VMs on shared infrastructure meets your security and compliance needs.
4. When to Choose ExaDB-D (Dedicated Infrastructure):
- Maximum Isolation Required: Your security policies, compliance regulations (e.g., certain financial or government standards), or internal governance demand physically isolated hardware.
- Utmost Performance Predictability: You need guaranteed performance levels based entirely on your workloads running on dedicated, non-shared resources.
- Large-Scale Consolidation: You consolidate numerous or very large databases onto a powerful, isolated platform. If the database storage exceeds 90TB, ExaDB-D would be more cost-effective, irrespective of the ECPUs required.
- Migrating Existing Exadata: Moving a significant on-premises Exadata workload to the cloud requires equivalent dedicated resources.
- Specific Compliance: Regulations explicitly mandate single-tenant hardware, even within the cloud.
5. Price Comparison
With ExaDB-D, you get dedicated usable storage of 240 TB. This allows you to allocate up to 192 TB for databases (without local backup) or up to 96 TB with local backup. Taking just the storage vault cost for 90TB in ExaDB-XS almost matches the infrastructure cost for 2 database servers (up to 1520 ECPUs) and 3 storage servers (up to 240 TB usable space). So you cannot determine if ExaDB-D or ExaDB-XS will be price-performant just by looking at the ECPU requirement.
Let me show this with two sample Bill of Materials (BoM). Since the blog template width is limited, here are the SKU descriptions used in the cost estimate.
| SKU | Exadata Database Service – ExaDB-XS |
| B109355 | Oracle Exadata Exascale RDMA Compute Infrastructure (ECPU Per Hour) |
| B107951 | Oracle Exadata Exascale VM Filesystem Storage (Gigabyte (GB) Storage Capacity Per Month) |
| B107952 | Oracle Exadata Exascale Smart Database Storage (Gigabyte (GB) Storage Capacity Per Month) |
| B109375 | Oracle Exadata Exascale Additional Flash Cache (Gigabyte Per Hour) |
| B109357 | Oracle Exadata Exascale Database ECPU – BYOL (ECPU Per Hour) |
| SKU | Exadata Database Service – ExaDB-D |
| B110629 | Exadata Cloud Infrastructure – Storage Server – X11M (Hosted Environment Per Hour) |
| B110627 | Exadata Cloud Infrastructure – Database Server – X11M (Hosted Environment Per Hour) |
| B110632 | Exadata Database ECPU – Dedicated Infrastructure – BYOL (ECPU Per Hour) |
Table 1: Large database storage footprint (90TB). ECPU allocation is very small, but ExaDB-XS is still expensive, and going with ExaDB-D makes it cheaper to scale.
| Part SKU | Part Qty | Instance Qty | Usage Qty | Unit Price | Monthly Cost |
| ExaDB-XS | $ 11,650.48 | ||||
| B109355 | 16 | 1 | 730 | $0.025000 | $292.00 |
| B107951 | 280 | 1 | 1 | $0.042500 | $11.90 |
| B107952 | 90000 | 1 | 1 | $0.115600 | $10,404.00 |
| B109375 | 0 | 1 | 730 | $0.000500 | $ – |
| B109357 | 16 | 1 | 730 | $0.080700 | $ 942.58 |
| ExaDB-D | $ 11,539.26 | ||||
| B110629 | 3 | 1 | 730 | $2.903200 | $6,358.01 |
| B110627 | 2 | 1 | 730 | $2.903200 | $4,238.67 |
| B110632 | 16 | 1 | 730 | $0.080700 | $942.58 |
| Difference | -1% |
Table 2: Smaller storage footprint (30TB). Plenty of ECPUs allocated on ExaDB-XS, still, it is cheaper than ExaDB-D.
| Part SKU | Part Qty | Instance Qty | Usage Qty | Unit Price | Monthly Cost |
| ExaDB-XS | $23,233.12 | ||||
| B109355 | 256 | 1 | 730 | $0.025000 | $4,672.00 |
| B107951 | 280 | 1 | 1 | $0.042500 | $11.90 |
| B107952 | 30000 | 1 | 1 | $0.115600 | $3,468.00 |
| B109375 | 0 | 1 | 730 | $0.000500 | $ – |
| B109357 | 256 | 1 | 730 | $0.080700 | $15,081.22 |
| ExaDB-D | $25,677.90 | ||||
| B110629 | 3 | 1 | 730 | $2.903200 | $6,358.01 |
| B110627 | 2 | 1 | 730 | $2.903200 | $4,238.67 |
| B110632 | 256 | 1 | 730 | $0.080700 | $15,081.22 |
| Difference | 10% |
In Summary, both ExaDB-XS and ExaDB-D offer the core performance and availability benefits of Exadata within OCI.
- Choose ExaDB-XS for elasticity, lower entry cost, smaller storage requirement and simplified management on shared infrastructure when physical isolation isn’t the top priority.
- Choose ExaDB-D for maximum isolation, larger database storage, performance predictability, and control on dedicated hardware, typically for mission-critical, large-scale, or highly regulated workloads.
