If you are working with Oracle databases I am quite sure that you know their engineered system portfolio and especially the Oracle Exadata. It is a piece of converged infrastructure which is designed to run Oracle DBs and only oracle DBs. The Vendor itself call it the fastest database machine of the world. The Nutanix HCI platform is really new and I became familiar with this technology over the last months. Because I have a lot of expierence with both, I thought it makes sense to compare both platforms running Oracle RAC DBs on it.
Virtualisation
Exadata: Since generation X6 it was possible to use so called “Exadata OVM” version which means to use a Xen-based hypervisor until generation X8-2. With the latest version the X8M-2 Oracle decided to move to a KVM-based HV. Mainly because of the switch of the internal networks which was based on Infiniband and is Ethernet now. The HV is very poor in features compared to others on the market. For example there is no GUI for the administration part or an online moment of VMs isn’t possible, also with the newer KVM-HV. On top there is a limitation of max 8 (XEN) / 12 (KVM) per server. At the end you have to consider virtualisation on Exadata more as a way to partition the machine, like split compute resources of CPU or memory to VMs, attach different VLANs to segregate different environments.
Nutanix HCI: As Nutanix started to consider virtualisation at day 1 it has far more capabilities like the Exadata. Usage of multiple HV like ESXi, AHV or HyperV is one big argument. Online tasks like movement of VMs or resizing is standard. Having a nice GUI like vCenter or Prism also simplifies day-by-day operations and allows API infrastructure management. There are just limitation based on the HV overall it can scale-out to 1000 nodes and 10.000 VMs.
Architecture
The infrastructure architecture couldn’t be more different between boths. Exadata is a classical converged infrastructure, so all components are close together in one or some more racks. It has a compute (DB Server), a network- (infiniband / RoCE) and a storage layer (storage cells). Through the very fast lossless network 40 Gbits (IB) or 100 Gbits (RoCE), protocol enhancements like RDMA and iDB the Exadata became a “beast” for database performance.
Nutanix is using the hyperconverged infrastructure approach where the compute- and storage layer merge together. The network layer still exists and connecting the nodes. Hereby it is recommend to use Ethernet with 10 Gbits or faster. In our environment we are using 25 Gbits. The beauty here is that storage is local and shared at the same time which is reducing latency and simplifies the administration. This means if I need storage I add a further node – there is no storage layer anymore like a SAN or NAS. It is more than recommended to use very fast storage like NVMe-SSDs. Newer implementations allow Intel Optane storage for instance.
Overall I have to state that adding virtualisation is adding a further layer. Assuming your running PDBs as well. You have 1.) The physical layer 2) The hypervisor 3) the VM and its OS 4) the Container-DB and 5) the Pluggable database. In a nutshell complexity in IT is increasing.
Administration
For this comparison I exclude tools which I need in the application VMs where the database is actually running. At the end those Oracle tools are anyway needed like SQLPLUS, DBCA, SRVCTL, CRSCTL and LSNRCTL.
| Oracle Exadata | Nutanix HCI | |
| Compute layer | XM / domu-maker | PRISM (GUI) / acli |
| Storage Layer | Cellcli | PRISM (GUI) / ncli |
| Network Layer | IB-cli and Cisco IOS-cli | Cisco IOS-cli |
As you can see for Nutanix less CLIs are needed and a GUI is present
Conclusion
After shed some light in the areas virtualisation, architecture and administration – It is quite clear that both platform comes from different decades and use cases. The Exadata which was intended as one big monolithic block for processing power where virtualisation was added later one allowing to partition the block. Nutanix HCI was created with a scale-out architecture relying on public cloud providers like AWS or GCP and more simple to manage.
My Opinion
Just focusing on the subjects flexibility and management Nutanix is clearly better in those categories. Another advantage is that it is not only for Oracle DBs, you can use also other db engines. Performance is another subject and in my next post I will share some benchmarks for both platforms.
