In general IT needs to listen to the Business.GOVERNANCEGovernance is the set of policies, roles,responsibilities, and processes thatguide, direct, and control how anorganizations business divisions and ITteams cooperate to achieve businessgoals.
Number of 9s Availability Percentage Total Annual Downtime2 99% 3 days, 15 hours3 99.9% 8 hours, 45 minutes4 99.99% 52 minutes, 34 seconds5 99.999% 5 minutes, 15 secondsFor a given software application or service, high availability is ultimately measured in terms of the end user’s experience and expectations. The tangible and perceived businessimpact of downtime may be expressed in terms of information loss, property damage, decreased productivity, opportunity costs, contractual damages, or the loss of goodwill.The principal goal of a high availability solution is to minimize or mitigate the impact of downtime. A sound strategy for this optimally balances business processes and ServiceLevel Agreements (SLAs) with technical capabilities and infrastructure costs.A platform is considered highly available per the agreement and expectations of customers and stakeholders. The availability of a system can be expressed as this calculation:Actual uptime/Expected uptime X 100%The resulting value is often expressed by industry in terms of the number of 9’s that the solution provides; meant to convey an annual number of minutes of possible uptime,or conversely, minutes of downtime.http://technet.microsoft.com/en-us/library/jj715263.aspx
All servers that belong to a server farm,including database servers, must physicallyreside in the same datacenter. Redundancyand failover between closely located datacenters that are configured as a single farm("stretched farm”) is not supported inSharePoint 2013.http://technet.microsoft.com/en-us/library/cc262485.aspx
Web frontendSiteLoad balanceCentral admin Central adminWeb frontendSiteWeb frontendSiteWeb frontendSite
Web frontendSiteLoad balanceCentral admin Central adminWeb frontendSiteWeb frontendSiteWeb frontendSitecontend
One farm is always offline (well standby offline)