HP Capacity Advisor 7.2 User Guide

Resource capacity
Workloads that specify utilization limits for a metric (for example, memory or disk I/O) can only
be placed on resources that define a capacity for the corresponding metric. In other words, if you
specified that a workload never exceed 100% memory utilization, that workload can only be
placed on a system for which total memory capacity is known.
Utilization limits
Every workload selected must have at least one utilization limit applied before using the Smart
Solver. This can be any type of utilization limit, including the default global utilization limit.
Headroom rating
The headroom rating shows the amount of available resource above the existing resource utilization
that will exist for the resulting solution in the simulation. Among the solutions that require the same
target systems, the solution with the tightest fit is shown.
Possible anomalies in the results
Load balanced results appear unbalanced
The solution may not look balanced because smaller systems generally are assigned a smaller
percentage of usage than larger systems, and very small systems may end up with no workloads
at all.
For example, a large 16 GB system at 87% memory usage has 2 GB of headroom, and a smaller
4 GB system at 87% has only 500 MB of headroom. Aiming for 87% usage on both systems would
not yield a balanced solution. Instead, a balanced solution is to fill the larger system to 87% and
fill the smaller system to only 50%. With this placement, workloads placed on either system will
have the same amount of headroom to grow (2 GB).
No apparent change from original configuration
The solution may be the same as the original scenario, and it looks as though no computation was
performed. Actually, with the current attributes and constraints, the Smart Solver could not find a
better solution than the current configuration of systems. This means that the current configuration
is the current best solution. A message displayed in BLUE text indicates that the results are not an
error (errors are displayed in RED text).
No apparent change on one or more systems
The solution may show no change on one or more destination systems. Thus, it may appear that
the Smart Solver did not include the server in its computations. In actuality, the Smart Solver
determined that as part of the best solution, it was best to leave these target systems with their
original configurations.
Fewer systems shown
The Smart Solver solution can contain fewer destination servers than were originally selected. This
occurs when the workloads fit on fewer servers than originally selected. For example, if servers A,
B, and C are selected as destinations, but all the workloads can fit onto servers A and B, then only
servers A and B are shown in the solution.
Smaller systems appear unused
The solution may not display smaller systems, making it appear as if the smaller systems were not
included in the Smart Solver computations. In actuality, when the Smart Solver attempts to place
the workloads on target systems, it accounts for the robustness of those systems. If the workloads
fit on larger, more robust systems and the smaller systems go unused, the solution will display only
the larger, used systems.
For example, if there are two large systems and two small systems, the solution may show only the
two large systems, and load balancing will occur only on those two systems.
Automating time-consuming simulations 95