Multiple hypervisors are typically deployed in a data center. Enterprises should be able to address more workloads and move them around from one infrastructure to another. Also, ISVs like Oracle prefer to provide better support on their proprietary virtualization platform like Oracle VM (based on Xen hypervisor).
Using a variety of technologies and also due to cost variances, data center administrators are increasingly finding themselves with a spectrum of virtual machines in their infra environment.
For a storage vendor it is essential to create interfaces with commonly deployed hypervisors. Most common ones used are:
- VMware
- HyperV (Microsoft, taking away market share from VMware)
- Xen Project (Oracle, Huawei, Citrix)
- KVM (RedHat)
Source: www.gartner.com/imagesrv/reprints/268500/268538/268538_1.png
For storage (Block or Object) vendors, developing and deploying Plug-ins is essential. Let's address the top two hypervisors deployed in enterprises, namely VMware and Microsoft HyperV and also fast growing relevant to the party Oracle VM.
VMware: To discover, provision, and monitor storage infrastructure, a storage specific vCenter plug-in needs to be implemented as an extension to the UI infrastructure that VMware provides out of box. There are strategies to build these plug-ins as embedded - being part of the VMware's application server called "Virgo-server" or as an external plugin on a management server running independently and exchanging metadata with Virgo-server using a custom interface. Both approaches have pros and cons and it largely depends on how many plugins (for other hypervisors or same) are needed that it justifies launching a dedicated management server.
HyperV: In case of HyperV for monitoring and management and accessing key functionality, SCVMM plugin need to be developed. Microsoft has an integrated management environment called System Center. SC manages virtual machines besides other services within Microsoft server ecosystem. To manage a storage, vendor needs to provide plugins that are available as Add-in on the SCVMM console.
OracleVM: Oracle is late entrant to virtualization party, but as usual eager to dominate. With acquisitions like Sun Microsystems and Pillar Data, Oracle seems set to homogenize the look and operations of data centres around its technologies. For now, there is not much the storage vendors need to provide other than what Xen supports to be accepted in oracle dominated data centers.
While these hypervisors may be deployed in a data center, to manage tasks and workflows, an orchestration layer is usually required. That’s where Openstack comes to rescue.
Cloud computing in a data center needs to be agnostic; you need to take workloads from one infrastructure to another. Enterprises need to have the brokerage between different hypervisors. Mixed hypervisor support is required for the following reasons.
- workload optimization
- flexibility in license cost
- centralized control panel
- flexibility to schedule tasks on any server
By creating Cinder plugins, storage vendors allow their customers to implement services and libraries to provide on demand, self-service access to block storage resources. In short, you provide software defined block storage via abstraction and automation on top of traditional block storage devices. Similarly, integration with SWIFT module is required to enable object storage with the Openstack.
Data Center Administrators prefer multi-hypervisor environments to leverage unique benefits provided by each one of them, - Costs and supportability are the two key parameters used to determine the choice of hypervisors. However, invariably a data center ends up becoming a messy enchilada of virtualization platforms, storage arrays and network devices. To ease the pain and improve adaptability of their solutions, data storage providers must provide plugins to access their functionality in a consistent way.
As they say, what cannot be fixed - must be managed. Storage and other solution providers manage the mess created by the diverse set of platforms by bundling the required plugins to get an entry into data centers.
In most cases, building plugins is a one time activity and hiring dedicated teams to build these plugins and to keep up with the changing needs of standardization (e.g. changes in VMware 5.0 to VMware 5.5 from Flash based UI to HTML5) is usually a distraction for the core development teams. To solve this, third party service providers provide floating teams with expertise in building the plugins on various platforms.