vCenter Server can leverage all the solutions for high availability discussed in detail in attached document. The actual solutions used depend on customer requirements. Picture shows the various solutions, their features, and their cost and complexity ratings. The more solutions that are used, the more expensive and complex they are. The choice should be dictated by minimum customer requirements for vCenter Server availability.
Unfortunately there are no industry standard values for mttr and mtbf for an x-86 server running a hypervisor. mtbf depends on the hardware and frequency of firmware and hypervisor related issues – the latter in turn is impacted by patch management procedures. So mtbf may vary between different environments. So how can we estimate these metrics? As SAP is typically virtualized after other non-SAP applications, you can gather operational statistics from existing production or non-production ESXi clusters to get estimates for mtbf and mttr. For mtbf, we would need to determine how often VMware HA events have occurred in any existing operational ESXi clusters. Few informal enquires I have made show frequency of failure around 1-2 times a year for an ESXi host and in some cases over a year without incident. For mttr are there any SLAs in place (for example server vendor services contracts) or can IT operations estimate a time they can repair or replace a faulty ESXi host in a production SAP cluster? As SAP business processes are mission critical such an SLA or understanding may be in place or required. Hence I will show results for a range of mtbf and mttr. The results are shown in the following table for mtbf = 90, 180 and 360 days and mttr = 2, 4, 8 and 24 hrs (I have estimated 1 year to 360 days).
Source: http://blogs.vmware.com/apps/2013/07/estimating-availability-of-sap-on-esxi-clusters-examples-2.html
Further links in pdf:
1. Disk Quorum and Clustering Requirement
2. vCenter Deployment and System Requirement
3. WSFC in VMware Environments
4. WSFC Failover Knowledge Base
5. vCenter Installation
6. Database Full Recovery Model for vCenter
7. Troubleshooting Guide for vSphere and vCenter 6.0
8. Creating a Windows Server Cluster
9. vCenter Server High Availability with Windows Server Failover Cluster and DFS 10. Estimating Application Availability in ESXi Clusters
11. VMware High Availability Analysis
12. Supported vCenter High Availability Options
Probablly best of them is VMware High Availability Analysis
http://blogs.vmware.com/apps/2013/07/estimating-availability-of-sap-on-esxi-clusters-examples-2.html
Source:
http://blogs.vmware.com/apps/2013/07/estimating-availability-of-sap-on-esxi-clusters-examples-2.html
vmware-vcenter-server-availability-guidevmware-vcenter-server-availability-guide
http://www.availabilitydigest.com/public_articles/0712/sap_vmware.pdf
