
108 The Green and Virtual Data Center
when work exceeds that point, corresponding response time will degrade
below acceptable. For example, peaks due to holiday shopping exchanges
appear in January, then drop off, and then increase again near Mother’s Day
in May.
Thresholds are also useful from a space capacity basis—for example, on
servers, determining that particularly applications can run statistically at up
to 75% utilization before response time and productivity suffer. Another
example would be establishing that storage capacity utilization to meet per-
formance needs for active data and storage is 70%, while near-line or offline
storage can be ...