First thing is that OCI is the only public cloud which supports bare metal and VMs using the same set of APIs, hardware, firmware, software stack and networking infrastructure. You can see the two models on the slide – Bare Metal instances are instances where customers get the full server. This is also referred to as single-tenant model. The advantage here is that there is no performance overhead, no shared agents and no noisy neighbors. On the other spectrum are VMs, where the underlying host is virtualized to provide smaller VMs – also referred to as multi-tenant model. The advantage here is flexibility in regards to choice of instance shapes.
All Oracle-provided images include rules that allow only "root" on Linux instances or "Administrators" on Windows instances to make outgoing connections to the iSCSI network endpoint (169.254.0.2:3260) that serves the instance's boot and block volumes. Oracle recommends that you do not reconfigure the firewall on your instance to remove these rules. Removing these rules allows non-root users or non-administrators to access the instance’s boot disk volume. Oracle recommends that you do not create custom images without these rules unless you understand the security risks.
So we briefly discussed about boot volumes early.
When any instance is launched (virtual machine or a bare metal) on an oracle provided image or a custom image, a new boot volume for the instance is created in the same compartment. That boot volume is associated with that instance until you terminate the instance. When you terminate the instance, you have the option of preserving the boot volume and its data. This feature gives you more control on the boot volumes of your compute instance. For instance .
It gives you the ability to preserve your boot disk content by keeping it when you terminate a compute instance: You can use the preserved boot volume for new instance creation.
Just like block volumes are replicated across ADs, the boot volumes are also highly durable as they are replicated across ADs automatically.
Boot volumes can also help in instance scaling. Since you can preserve the boot volume when terminating an instance, the preserved boot volume can be used with a new instance of different shape, which can have more OCPUs.
The launch times are much faster than earlier.
All boot volumes are encrypted at rest like block volumes
And it also helps us in troubleshooting or repairing boot disks.
To use boot volumes, there is nothing special that one needs to do. Moving forward all instances that are launched will be done using boot volumes having all the features we talked earlier.