When it comes to deployment options for Oracle Cloud VMware Solution, you can choose between two options: A single-availability domain deployment, which is the standard deployment type, and a multiavailability domain deployment, which is typical if you require a software-defined data center (SDDC) with a high service level agreement (SLA) to run mission-critical workloads.
With Oracle Dedicated Region Cloud@Customer, Oracle Cloud VMware Solution can also support a VMware vSAN stretched cluster. This solution provides high availability and resilience across data centers with a recovery point objective (RPO) of zero and a low recovery time objective (RTO).
In this blog post, we take a deeper look at the different deployment options and review their respective requirements, considerations, limitations, and benefits.
The single-availability domain deployment option for an Oracle Cloud VMware Solution SDDC has two scenarios: One with DenseIO shapes and VMware vSAN as the storage option and the other with standard shapes and Oracle Cloud Infrastructure (OCI) Block Storage as the storage option.
In a single-availability domain deployment with DenseIO Shapes and VMware vSAN as the storage option, the Oracle Cloud VMware Solution cluster stretches across three fault domains within a single availability domain. This standard deployment type supports an availability SLA of 99.95%. With this deployment option, the bare metal hosts are distributed across the three fault domains for maximum resilience within a single availability domain.
In a single-availability domain deployment with atandard shapes and OCI Block Storage as the storage option, the Oracle Cloud VMware Solution cluster stretches across three fault domains within a single availability domain. This standard deployment type supports an availability SLA of 99.95%. With this deployment option, the bare metal hosts are distributed across the three fault domains for maximum resilience within a single availability domain. These bare metal hosts then connect to OCI Block Storage because the standard shapes don’t provide local storage capacity to create a vSAN datastore.
This deployment option is only available for single-availability domain deployments because OCI Block Storage is currently not mirrored across OCI availability domains.
The multiavailability domain deployment option for an Oracle Cloud VMware Solution SDDC is only supported with DenseIO Shapes and VMware vSAN as the storage option. This option is fully unique and only supported with Oracle Cloud VMware Solution on OCI.
In a multiavailability domain deployment with DenseIO shapes and VMware vSAN as the storage option, the Oracle Cloud VMware Solution cluster stretches across three availability domains within an OCI region. This deployment type supports an availability SLA of 99.99%.
With this deployment option, the bare metal hosts are distributed across the three availability domains for maximum resiliency and availability within a OCI public cloud region.
The multiavailability domain deployment is only available in OCI public cloud regions with at least three availability domains. For multiavailability domain deployment, you must reserve at least 33% failover resources to be able to withstand the loss of an availability domain. The same applies to the vSAN configuration if the solution use three nodes, which is the minimum that the vSAN policy must be according to RAID-1 with FTT-1. This configuration allows a single bare metal host or availability domain to fail.
A multiavailability domain deployment must always scale equally. If you start with the minimum deployment of three nodes, you must scale out in multiples of three nodes to keep the host count evenly distributed across all availability domains. Unequal scaling can result in resource utilization problems and data loss if the bare metal hosts or an entire availability domain fail.
The stretched cluster deployment option is currently only available for Dedicated Region Cloud@Customer. This deployment is only available for customers that can meet the minimum requirements for data center interconnectivity required to set up and operate VMware vSAN stretched clusters.
This special setup requires at least two Dedicated Region Cloud@Customer installations within customer data centers and a third site or data center to host the VMware vSAN witness appliance. It has the following distinct requirements:
Round-trip time (RTT) between data sites must be below 5 ms.
Bandwidth between data sites must be at least 10 Gbps dedicated.
RTT between data sites and witness must be below 200 ms.
A third DRCC installation with Oracle Cloud VMware Solution or a customer-managed VMware environment at the third site or data center to host the VMware vSAN witness appliance
Data center interconnectivity. Meeting the requirements in full is the responsibility of the customer.
The stretched cluster solution works as a failover cluster to protect against a data center outage and required to reserve 50% resources for vCPU and vMEM and 50% for VMware vSAN capacity.
Choosing the right deployment option isn’t always an easy decision and is usually driven by availability requirements. However, as we outlined in this blog, the high availability option with multiavailability domain deployments can come at a high cost because the cluster must scale evenly across availability domains. Also, with no support for OCI Block Storage to increase only storage if necessary, multiavailability domain deployments must always scale horizontally to scale vCPU, vMEM, and vSAN evenly.
Stretched cluster solutions are the most complex when it comes to sizing, capacity planning and operations so it is valuable to think about transferring the high availability into the application layer rather than into the infrastructure layer to be future proof, reduce infrastructure cost, and complexity.
Finding the correct deployment options is both an important and complex decision. With Oracle Cloud VMware Solution, our cloud architects can help to explore your use case and work to identify the best deployment option for your business. To get connected with an expert and kickstart the process, use the Oracle Cloud VMware Solution contact form.
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Thomas Thyen is a Cloud VMware Solutions Specialist within the Technical Cloud Engineering Organization at Oracle mainly working on Oracle Cloud VMware Solution and integration with the VMware product stack and 3rd party products. He is specialised in technologies like VMware vSphere, VMware vSAN, VMware NSX, VMware HCX, VMware vSphere Replication, VMware Site Recovery Manager, VMware vRealize Suite, VEEAM Backup & Replication and Citrix Virtual Apps & Desktops.