Hi Saad
Answering this question requires in-depth knowledge of your architecture, the profile of applications running, the infrastructure, and a lot more. There are many details to be aware of.
As a VERY broad response, containers usually make more efficient usage of the resources. Containers talk directly to the host SO (avoiding the hypervisor), making calls a little bit cheap.
But the main advantage of containers is not the performance, but the density. As containers "share" the underlying OS, they are much lighter than VM. This density allows running dozens of containers on a server where only a bunch of VM can run.
Containers also share persistence layers that are both non-writable and common to several images. So, if your container images share, say, the same base image, the amount of disk space saved is enormous.
This saving is especially significant when the infrastructure runs on an external cloud provider, where every CPU cycle and MB transferred have a cost.
Anyway, containers are not for free. Running any container management platform (say OpenShift) require dedicated infrastructure, knowledge of container management, access control, etc. Nothing new in comparison to VM management platforms, but worth having it in mind, as this is a high cost when starting with containers.
As said, many details can change the numbers. In general, and long-term, containers tend to be the most cost-saving option, if you are willing to pay the initial migration costs.
Hope it helps.
Jordi Sola
P.S. Most banks are migrating from VM-based solutions to Container-based solutions. If your applications are something similar to what they run, you can make sure they counted all dollars.
