Myths & realities about OpenStack affecting VMware
There are many people on the web who have argued about Openstack affecting VMware which even has impacted the VMware course aspirants. Where the truth of the matter is that Openstack Compute supports the VMware vSphere is the product family enabling access to advanced features like Dynamic Resource Scheduling (DRS), and Motion, High Availability.
OpenStack is an open-source software used for cloud computing that is free of cost. On a regular basis, OpenStack deploys various services like the infrastructure by making services like virtual servers available to customers.
Whereas when you look into VMware you’d know that VMware operates on the basis of vCenter driver that allows Nova-Compute Service to communicate with a VMware vCenter server. We know that VMware works along with EXS however, it is the VMware vCenter drivers that enables nova-compute services to communicate with a VMware vCenter servers that are entitled to manage ESX host Clusters. Furthermore, theses drivers aggregate ESX hosts one large hypervisor entity for each of the clusters computing the schedules. The reason being an individual ESX host is not exposed to the scheduler. Compute schedules to the granularity of clusters and vCenter uses DRS to select the actual ESX host within the cluster. When a virtual machine makes its way into a vCenter cluster, it can use all vSphere features.
High-level architecture
If you look at the above diagram You’d find that the OpenStack Compute Scheduler looks at 3 hypervisor corresponding to clusters in the vCenter. Nova-compute, on the other hand, contains VMware Driver, that can run with multiple Nova-compute services. It is recommended to run with one Nova-compute service per ESX cluster hence ensuring that as compute schedules at the granularity of the Nova-compute services are also effective to schedule at the cluster level. Where a VMware driver in return inside the Nova-compute interacts with the vCenter APIs for the selection of an appropriate ESX host from within the cluster. Where when looked internally a vCenter uses DRS for placement. Even the VMware vCenter driver interacts with the Image Services just so that it can copy the VMDK image service back-end store.
In the image, if you look at the dotted line which is connecting the Shared Datastore it shows that is the VMDK images being copied from the OpenStack Image Services to the vSphere datastore. VMDK images are computing (cached) in the datastore where the copy operation is required in the first attempt when the VMDK images are used.
Once the OpenStack Boots a VM into a vSphere cluster, this makes the VM visible in the vCenter and allows the vSphere to access the advanced features. Once the VM is visible in the OpenStack dashboard which one can manage like any other OpenStack VM. One can also perform advanced vSphere operations in vCenter while configuring the OpenStack resources like VMs using the OpenStack dashboard. The image, however, doesn’t show how networking fits into the architect where OpenStack Networking & Nova-Networking are also supported.
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