Task: Planning Server Consolidation

This section starts with a generic procedure (“Planning Server Consolidation”)for consolidating servers followed by an example of server consolidation (“Example: Consolidating to an Existing Server: Stacking Programs”).

Planning Server Consolidation

Consolidating workloads to a new server or to free up an existing server is a common task. Capacity Advisor can help make the decisions about how to consolidate the workloads informed ones.

There are three fundamental approaches to consolidating servers:

Stacking workloads (representing applications) into standalone servers or nPartitions.
Stacking virtual machines into standalone systems or nPartitions.
Stacking nPartitions and virtual partitions into complexes.

The task description below is based on stacking Virtual Machines. For other approaches, the step describing editing the scenario would be different.

Prerequisites. To plan for consolidating servers:

You should be familiar with Capacity Advisor operations (see Basic Operations).
You must be logged in to HP Systems Insight Manager (see Accessing Capacity Advisor).
You must have already collected data on the systems of interest (see Collecting Data).

Procedure 5-1 To Consolidate Server Loads

Determine the Systems to Consolidate
This should include:
- The servers with loads you wish to consolidate.
- The server you wish to consolidate the loads to (this can be a new server or an existing one).
Be sure to take into consideration the following:
- Connectivity: are the LANs and SANs needed by all the systems to be merged available to the server being targeted as the new host?
- Security: do any of the systems require isolated networks; are any of the systems subject to HEPA requirements?
- Ownership: are all of the applications and systems to be combined owned by a common organization or are all the owners agreeable to the consolidation?
- Licensing: are there any licensing restrictions that will prevent moving the applications; are there any advantages to moving the applications to a common server (such as combining applications using SAP or Oracle licenses to a single server)?
- Quality of Service: are the Quality of Service requirements for each application and server well understood?

Create a Scenario

Follow the procedure in Creating a Scenario; remember to select the servers with the applications you wish to consolidate and, if it is not already in the scenario, the server you are targeting for the consolidated loads.




	NOTE: You cannot specify a Virtual Machine (VM) directly. Specifying a VM Host will cause all VMs hosted by the host to be included in the scenario. There is no way to include a single VM within a scenario without including the VM Host and all VMs managed by that VM Host.

Edit the Scenario
In this part of the process, you will build a model of the new configuration you wish to evaluate.
Follow the procedure in Editing a Scenario to edit the newly created scenario. While editing the new scenario, you will need to:
1. Set up the host system, including making it a VM host. This involves following the procedures in either Creating a System to create a system with the characteristics of the new system or Editing a System to change the characteristics of an existing system to reflect any changes being made in the existing host.
2. Create a VM for each of the systems you are planning to consolidate by following the procedure in Creating a System.
3. Move the workloads from the systems you are planning to consolidate to the appropriate VMs by following the procedure in Moving a Workload. At this point, you can adjust the cpu and memory usage to model any projected change in the required resources or to accommodate differences in architecture and software configuration, using the procedure described in Editing a Workload. An example of applying the platform multipliers to accommodate differences in architecture is provided in the help for the Move Workload screen.
  NOTE: The bar-graphs showing load and memory usage provide a quick estimate of the effect of moving each workload.
Estimate the New Quality of Service
Generate a report on the scenario following the procedure in Generating a Report
Repeat the Editing and Estimating Steps if Necessary
It is sometimes necessary to run through a number of variations on the scenario to determine the best consolidation strategy. You can repeat the preceding two steps to determine the optimum configuration, including whether adding Temporary Instant Capacity (TiCap) processors could help optimize your cost structure.

Example: Consolidating to an Existing Server: Stacking Programs

This example demonstrates how Capacity Advisor can be used to plan for the simplest method of server consolidation: stacking programs. Three servers were set up over the last few months to support applications. Now that there is good data on the utilization, it is a good time to see if consolidating the applications can free up resources for other uses.

The steps referenced in the following titles are from the procedure “Planning Server Consolidation” presented above.

Step 1: Determine the Systems to Consolidate

This step requires a profound knowledge about the systems. Many questions need to be answered about each system. Different consolidation models make different questions appropriate and others inconsequential. The questions listed below are derived from the questions in the generic procedure provided above.

What set of patches (patch level) is required by the applications (this does not matter if virtual machines are used for consolidation)?
What changes to settings of kernel tunables have been made (this does not matter if virtual machines are used for consolidation)?
What are the licensing requirements for the applications?
Who owns each of the systems and, if they are owned by different organizations, are they agreeable to the consolidation?
What are the security requirements?
What are the networking requirements (LAN and WAN)?
Are there Storage Area Network (SAN) requirements?
How stable are the applications? All of them should be test and development systems or productions systems.

This list is simply illustrative, many other questions may need to be answered for your particular environment.

For the purposes of this exercise, the following three systems are being considered for consolidation:

puny01v0
puny01v2
puny01v4

Each of the three systems has two processors and:

Is running applications based on the same database program, which is licensed per CPU
Is running the same operating system, with the same set of patches
Requires the same settings of kernel tunables for the database application
Uses the same LAN
Uses the same SAN
Has minimal security requirements that are adequately provided by the corporate firewall

Step 2: Create a Scenario

Create a new scenario:

Select OptimizeCapacity AdvisorCreate Scenario... from the upper menu-bar.
Click in the check boxes beside the systems to include in the scenario on the Select Systems for the new Scenario screen.
Click the Next button.
Fill in the Scenario Name and the Description fields.
Click the Next button.
Check the values presented on the Verify Scenario Parameters screen of the Create New Scenario wizard and then click the Finish button.

Step 3: Edit the Scenario

Click the name of the scenario just created in the list presented on the VSE Management: Capacity Advisor screen to open the Capacity Advisor - Edit Scenario window. The selected systems will be listed on the System tab. The bar graphs show the peak utilization for data collected this week.

The weekly data is representative of recent utilization and can be calculated quickly, but doesn't always give a comprehensive picture.

For a more comprehensive picture, look at a month's data. Change the simulation interval to a month by clicking the first drop-down list of the Simulation Interval (the word “Week”) and selecting Month from the list. Once the screen has refreshed, new information about resource utilization is available: a number of the CPU and memory utilization peaks have increased.

Look at the profile for puny01v2, the system with the heaviest load, by clicking the first bar graph beside its name.

There is a single peak that almost reaches to total available CPU resource, and a few that make it into the 75% utilization range. Examining the tabular summary provides more insight into the situation:

Average utilization is about a quarter of the available resource, while 90th Percentile is under a half, less than a single CPU.

Since puny01v2 already has the most memory in it, consolidation of the applications from the other systems to it makes sense.

Add Processors to Puny01v2

The first step is to add processors to puny01v2:

Click the Close button to close the profile viewer.
Click the check box preceding puny01v2 in the list of systems.
Select What-If ActionEdit System... from the lower menu bar.
In the resulting Edit Scenario - Edit System screen, increase the number of processors to 5 (two of the systems at almost 100% and one just under 50% utilization of two processors each). This will represent moving additional processors from the other systems into this one.
Click the Next button.
The CPU Utilization bar graph for puny01v2 shows about 40% utilization, about 2/5ths of the available processor resource.

Move Workloads

Next, move the workloads from the other two servers to puny01v2.

Click the Workload tab to open it.
Click the check box preceding puny01v0.fc.hp.com.
Select What-If ActionMove Workload... from the lower menu bar.
Click the radio button preceding the target system, puny01v2.
Notice that the CPU Utilization bar graph for puny01v4 indicates that utilization exceeds available resource, while the bar graph for puny01v2 shows a moderate increase in the CPU utilization. It is not necessary to adjust the CPU or memory multipliers, since no virtualization has been used and the processors and operating systems are the same for all the workloads. However, the Memory Utilization bar graph for puny01v4 has the broken bar that indicates insufficient memory to handle the new load. The system will need more memory.
Click the OK button.
Next, move the remaining workload. If puny01v0.fc.hp.com is still selected, click the check box preceding it to clear the check mark.
Repeat the steps above to move the puny01v4.fc.hp.com workload to puny01v2.
Click the OK button.

Increase the Memory

To provide adequate memory, edit the system again.

Click the System tab to open it.
The system puny01v2 should still be selected, so select What-If ActionEdit System... from the menu bar.
On the resulting Edit Scenario - Edit System screen, change the memory size to 32 GB, which represents moving memory from the other two servers to this one. While it might appear that 150% of the memory currently available to puny01v2 would be adequate, the scenario values for memory utilization only account for the memory used by the workloads, not the operating system overhead memory usage such as the data buffer cache.
Click the OK button.

Step 4: Estimate the New Quality of Service

For a quick estimate of the Quality of Service of the new configuration, click on the CPU Utilization bar graph for puny01v2. Notice that the CPU utilization graph peaks above 3, but never goes into the 4 processor range. One of the processors can be removed.

Click the Memory radio button to check on memory utilization. The graph clearly indicates that memory utilization is steady, with plenty of margin for operating system overhead. Collecting data on the system after consolidation can provide a better picture of how much memory is actually used by the system once it is deployed.

Further Analysis

Combining applications from the three servers leads to a reduction by two of the number of processors required. Using peak of sums modeling provided a clearer picture of what is happening than the sum of peaks model used in traditional capacity planning and accounts for one of the two processors being freed up. The number of licenses required for the underlying database application has also been reduced by two. Returning to the CPU utilization profile by clicking on the CPU radio button and inspecting the Interval Metric Summary table for CPU utilization:

The 90th Percentile level indicates that 90% of the time, less than 2 processors are required. Would it be possible to reduce the number of processors further?

Generate a Report on the Scenario

To investigate that, generate a report on the scenario:

Close the Capacity Advisor - Edit Scenario window.
The scenario used to plan consolidation should still be selected in the VSE Management: Capacity Advisor window. If not, click the radio button to select it.
Select ReportCapacity Advisor report... from the lower menu bar.
Make sure summaries and utilization profiles for the systems and workloads are selected in the first frame of the Capacity Advisor - Create Utilization Reports wizard.
Click the Next button.
Click the Finish button on screen two of the wizard.
Click the “Browse Report” link.
Click the puny01v2 link to view the report.

Using the Report

This report combines many tabular summaries that provide detailed descriptions of the utilization of processor and memory resources. The one most critical here is the Time spent at or above each percent of allocation. table. Scroll down to see it.

From the 60% line in the table, with 0.02% of the time spent at that level, only an absolutely mission critical application would require more than three processors. Dropping down to the 40% row, with 2.59% of the time spent at or below it, some applications might be able to tolerate dropping down to 2 processors; it is a business requirement decision to make.