Appendix D: Capacity Management : Organization Virtual Datacenter-Specific Capacity Forecasting : Determine Trending Variables : Determining the Trend
   
Determining the Trend
It is important to understand that the rate of increase dictates how far in advance additional organization virtual datacenter resources need to be purchased. The following table presents a sample virtual machine forecast for a quarter along with sample “time to purchase” value.

Table 17. Sample Organization Virtual Datacenter Trending Information
Attribute
Value
ΔNcpuUC
12
ΔNmemUC
12
ΔNVGB
360GB
Tpurchase
2 weeks
NcpuUC,cluster
320
NmemUC,cluster
717
 
In this example, NcpuUC,free and NmemUC,free represents the number of free resources within an organization virtual datacenter at which point additional organization virtual datacenter resources should be ordered. To determine the trigger point for ordering use the following equation if no pipeline data exists.