ExaCC vs. ExaCS – Which One is Right for You?

Exadata has been Oracle’s gold standard platform for running mission-critical Oracle databases for over a decade. Oracle is extending the availability of Exadata onto the cloud by offering it in two flavors: Exadata Cloud @ Customer (ExaCC) and Exadata Cloud Service (ExaCS)

If you want to leverage the power of Exadata to run your Oracle databases but don’t want the hassle of maintaining the hardware on your premises, one of these options may work best for you.

Let’s dive in and understand these offerings in detail.

Exadata Cloud @ Customer (ExaCC)

Oracle deploys Exadata on your data centre premises and manages (monitors, patches, troubleshoots) the infrastructure. You get access to Oracle Cloud service offerings with the underlying infrastructure running on Exadata on premises.

Pros:

1. Colocation. There are certain business requirements that mandate the data sit on a company’s premises. The requirement could be very low latency for connections between your application and databases or regulatory requirements for health or financial data. Having Exadata run within  your company’s firewall will meet these requirements.
2. Autonomous Database. Oracle’s latest database offering, the Autonomous database, which is a service offered on Oracle cloud, can be deployed using ExaCC.
3. Reduced capital expenditure. Since the Exadata systems with ExaCC are still owned by Oracle, the customer only pays a subscription for the service used. This could result in lower costs when compared to owning and managing your Exadata on premises.
4. Service Encapsulation. Hardware components like the physical compute nodes, network switches, storage servers etc., are patched remotely by Oracle. The patching is performed in rolling fashion in a manner that preserves service availability throughout the updating process, albeit with some performance impact for the duration of the patching.

Cons:

1. Lock in.  The customer needs to sign a minimum four-year contract with Oracle to provision the hardware on premises.
2. Scalability. Exadata full rack comes with a standard eight compute nodes, fourteen  storage nodes configuration and these configurations can be customized. Scaling beyond the initial deployment will require an additional ExaCC rack provisioned on premises, which is a time-consuming process.
3. Availability. An on-premises Exadata system has redundancy built into every layer, but at the end of the day, it still is just a single rack and cannot offer the high availability of Exadata systems deployed on Oracle public cloud.
4. Costing Strategy. Customers pay a fixed monthly payment for Exadata infrastructure usage, which depends on the configuration of Exadata that was provisioned, in addition to the payments for hourly OCPU consumption. Overall, this will lead to a significantly larger bill when compared to an ExaCS deployment.

Exadata Cloud Service (ExaCS)

This service is delivered using Exadata racks that are provisioned within an Oracle public cloud. The service is available in quarter, half and full-rack configurations.

Pros:

1. Scalability. ExaCS service with X8M can scale on demand, as opposed to ExaCC service which cannot. Scaling with Exadata X6, X7 or X8 versions would require moving the workload to the larger shape. This will typically require using a backup to restore the database or using Dataguard. Autonomous database service is offered on ExaCS as well and can automatically scale to 3X the initial OCPU allocation during periods of peak usage.
2. Service Encapsulation. Oracle patches the underlying infrastructure, similar to an ExaCC deployment. Customers can control when and how they deploy the pre-staged VM OS, GI and DB softwares.
3. Database Features. ExaCS runs on Enterprise Edition, Extreme Performance version which includes all DB options and EM packs by default. No separate licensing is required for individual packs.
4. Cloud Integration. If you have applications hosted on Oracle Cloud, be it using compute, containers or cloud functions, deploying ExaCS on the same region and availability domain as the application would lead to better network throughput to the database.
5. IT Cost Footprint. The footprint of your IT need not be large to justify the expense of running Oracle databases on ExaCS. The pay-per-use model helps keep costs down for small deployments while providing all the benefits of Exadata performance.

Cons:

1. Location. If your data needs to reside on premises for any of the reasons we discussed above, ExaCS may not work for you.
2. Latency. Your application runs on your data centre and the nearest Oracle Cloud region might be geographically quite far from you, so network latency might be a concern with ExaCS deployments.

The choice between these two services will depend heavily on your particular workloads and requirements. Hopefully, this post gives you a starting point in choosing the one that suits you best.

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