Availability of the applications is one of the important requirements for business critical applications. The vSphere platform provides capabilities to protect against hardware and software failures to meet the stringent SLA requirements of business critical applications.
Virtualized applications can avail of features such as vSphere HA protects from HW failures by restarting virtual machines on surviving hosts if a physical host were to fail. vSphere FT (Fault Tolerance) protects critical servers such as load balancers and other central servers with a small footprint (1vCPU) with zero downtime in the event of HW failures.
vSphere App HA for Application level protection for supported applications. Third party solutions that leverage vSphere Application Awareness API such as Symantec Application HA , NEVERFAIL, etc. layer on top of VMware HA and provide monitoring and availability for most of the common business critical applications.
The type of licensing impacts the cluster design for SAP virtualization. SAP is supported on most common database platforms such as SQL, Oracle, DB2 and SYBASE. When customers procure SAP, they can choose to buy the database licensing through SAP or purchase it directly from the database vendor. This decision impacts the cluster design for virtualized SAP environments.
Let us look at these two scenarios and their impact on the design.
Scenario 1: Database License procured from the DB vendor for SAP:
Database vendors have differing but usually very restrictive policies regarding virtual machines running databases. The cost of licensing databases in the extreme case could force a customer to license for the entire cluster, even though the database could be using only a small subset of the resources. Due to the uncertainty and the risk involved with DB licensing in this situation, it might be prudent to separate the entire database workload into its own cluster. By separating the entire database workload, the physical hardware used for databases can be isolated and licensed fully. Since only database workloads exist in this cluster one can achieve consolidation and efficiency for databases. The main disadvantage is the added overhead of having a separate cluster for databases. Since SAP landscapes have many modules with each module having its own individual database, creating a separate DB cluster with a good number of hosts is worthwhile and justified. Continue reading →
Over the past few years, there has been significant acceleration in adoption of the VMware platform for virtualization of business critical applications. When vSphere 5 was introduced with its initial support for up to 32 vCPU many of the vertical scalability concerns that existed earlier were addressed. This has been increased to 64 processors with the later vSphere 5.x releases ensuring that more than 99% of all workloads will fit vertically.
Having personally worked in IT infrastructure for more than 20 years with a strong focus on implementing and managing business critical applications, I see a general reluctance from application owners to virtualize business critical applications. When virtualizing business applications there are many critical factors one should consider. I seek to address the typical concerns of application owners about Virtualization with this multipart series on Virtualizing BCA. Continue reading →