Starting from version 19.11 of the Oracle Database Appliance software bundle, OLVM will definitely replace OVM server as virtualization engine. This change has quite a big impact as there will be no more virtualized specific deployment. Bare metal will come as a standard for all ODAs, and creating VMs for applications, or even databases, will be possible on top of that, for sure if you need them. And you can decide later to use virtualized machines. For now, 19.11 not being yet available, you’ll have to decide to deploy 19.10, not available for full virtualization support, and 19.9, the last release for OVM based virtualization. Which one should you use?
OVM server stands for Oracle Virtualized Machines server. This comes on top of Xen, an 18-year old hypervisor also available in other commercial products, like Citrix XenServer. The first goal of OVM server on ODA was to allow all configurations of cores regarding the license (for example, bare metal X3-2 ODAs were only supporting 4+ cores, when virtualized mode started from 2 cores). The second goal was to benefit from the remaining cores on the system to run your applications, most often those connected to the databases. It made sense because ODAs were expensive servers, so buying a 2-node appliance with its dedicated storage for only using a pair of cores for a few databases was not that interesting.
In 2016, Oracle put “lite” ODAs on the market with a brand new CLI (odacli) and without virtualized mode. Virtualization was only possible on these servers with KVM, which is a virtualization tool provided within the Linux OS, but without the possibility to dedicate some cores to the database and the others to VMs. HA ODAs were still compatible with the OVM based virtualized mode, but only bare metal mode was using the brand new CLI.
Oracle did a lot of work on ODA, especially regarding the odacli features. These features have not been back ported to oakcli, and oakcli is basically stuck to what’s were available 5 years ago. No GUI, no Data Guard feature, no backup management, no repository, no jobs, … Going back to oakcli after using odacli is a big step backward.
If you want to use virtualized machines on ODA, you have 2 options. Use the virtualized mode and get stuck with oakcli (and it’s also limited to HA ODAs) or use the bare metal mode, but hard partitioning is not supported for the VMs, meaning that you will run your applications on the cores dedicated to your DBs.
Virtualized mode is still available up to 19.9 version of the ODA software bundle. This software bundle not being too old, you could think that it’s the solution to adopt. Current bare metal version is 19.10.
Lite models brought huge popularity to ODAs, most of the customers are using these models. Some customers still need HA ODA, but most of them are deployed in bare metal mode. As a result, I think that more than 90% of running ODAs are using odacli stack.
Days of OVM server are numbered. Starting a new project in version 19.9 on ODA X8-HA this year may not be a good idea. If this solution will do the job, you will probably need to patch your ODA for security reason during the next years, and this would probably be a problem. Because patches are only bundle patches, you patch everything or nothing.
OLVM (Oracle Linux Virtualization Manager), will completely replace OVM server starting from 19.11. OLVM adds hard partitioning (and much more) on top of KVM, meaning that it will have the same license flexibility as OVM server.
I heard about a migration path currently being prepared by Oracle for going from OVM server to OLVM, but it’s surely quite a tough job and I would definitely prefer to do a reimaging instead of a complex patching if I had to choose. And I don’t think that a virtualized ODA could get future patches: you’ll probably stay in 19.9 for a while.
Nobody will prevent you to start with OVM server and you could probably switch to OLVM later, but you’ll have to change quite a lot of procedures, as odacli and OLVM are totally different tools compared to oakcli and OVM server. This will imply a lot of work from your side.
In terms of support, OVM server premier support is already over, but in the particular case of ODA, it’s probably still supported for a year or two, as it’s part of your ODA configuration. But ask this question to Oracle to make sure.
For a new project, I would not go on virtualized ODA 19.9, I would better deploy my ODA in 19.10 bare metal mode, play with it and get trained on it in the next months, and upgrade to 19.11 as soon as it will be available. This is because I want to deploy technologies that will fit my needs for the next 5 years. OLVM with odacli and 19c is probably the most convincing bundle for that.