1. Capacity Planning in a Virtual Environment
Chris Chesley, Sr. Systems Engineer

2. Today’s Objectives 2 most important tasks in capacity planning
Resource utilization
Boundaries in a virtual environment
Overview of the problems often encountered in a virtual environment.
How to identify current performance bottlenecks
How to find capacity in your environment
How to optimize your virtual machines
How to identify wasted storage

3. Capacity Planning Resolving performance bottlenecks
Identify where you have performance issues (are VMs getting needed resources)
Quickly resolve current problems
Use proactive analysis to avoid future performance issues
Optimize your virtual environment
Insure that each VM is using the resources assigned to them
Maximize your density of VMs per core or per host
Find wasted storage
KEY POINT not like windows where the entire system was dedicated to one application. Shared resources- more similar to mainframe.
Performance = how well you manage capacity (shared resources)

4. New vs. Old Data Center Pre-Virtualized Data Center
One application – One server
No sharing of memory and CPU
Limited sharing of storage
Virtualized Datacenter
Shared memory and CPU
Massively shared storage
Performance = capacity
Vmotion/DRS – Dynamic nature
Change from known to unknown state when VM added or changed
KEY POINT not like windows where the entire system was dedicated to one application. Shared resources- more similar to mainframe.
Performance = how well you manage capacity (shared resources)

5. Takeaway
If not closely monitored and managed, sharing of resources will lead to performance problems and downtime.
Windows environment- monitor servers. Now resources need to be monitored.

6. Resource Utilization What’s shared Physical CPU / Cores (not sockets)
Physical Memory
Physical Disk
Storage (how many GB am I using)
I/O (reads, writes, disk latency, disk queue latency)
Physical Network

7. Boundaries in Virtual Environments
Capacity issues occur at any level or resource type
VMs
Host
Cluster
Resource Pools (Vmware only)
Data Center
Key- performance bottlenecks can develop at multiple levels.
Types: Memory storage cpu netowrk disk io

8. How to Identify Current Capacity Bottlenecks
Out of the box Management consoles: vCenter client (Vmware) and Hyper-V Manager or Virtual Machine Manager (Hyper-V):Real time per-host stats, per-cluster, and per-VM statistics
Esxtop (Vmware) or PerfMon (Hyper-V): per-host statistics
VIM API and SDK: allows software to collect only the statistics they want
Esxtop expands upon the statistics offered by the VI client by showing statistics like number of dropped packets. It also has some configuration information. Much of this is also in the VI client, though the information may be distributed in various parts of the client.

9. Performance Monitoring Options
For every Cluster, Resource Pool, Host, and VM, using VirtualCenter to examine memory, storage, CPU and network utilization over a period of at least 1 week
Very time consuming process
(Clusters + Resource Pools + Hosts + VMs) X 5 resources (CPU, storage, RAM, network, disk i/o) = # of charts to review
e.g. (3 Clusters +3 RPs+ 50 Hosts VMs) X 5 = 2,780 charts to examine
Requires ongoing attention: at least several times a week

10. Identifying Available Resource Capacity
Select a Cluster, Resource Pool, or a Host
Get info on available memory, storage, CPU, disk i/o, and network i/o
Apply an average VM footprint to every resource type to see which resource you will run out of first
That’s how many more VMs you can fit into Hosts, Clusters, or Resource Pools
Where do I put new VMs?

11. Identifying Available Resource Capacity
Apply an average VM footprint to every resource type to see which resource you will run out of first
That’s how many more VMs you can fit into Hosts, Clusters, or Resource Pools
Where do I place new VMs
Data Center view – Active/Active
DR Data Centers may have capacity

12. Predicting Future Capacity Bottlenecks
Model additions of new VMs
Understand current utilization on all resource types
Make necessary changes to compensate for current and future growth
Implement iron clad change control process
Maintenance window and workload requirements
Cluster failover configuration
Resource Pool configuration
Powered down VMs

13. Optimize your virtual machines
Very easy to create VMs, not easy to know how many resources to give them.
No automated clean up
According to the Information Technology Infrastructure Library (ITIL), capacity management is the discipline that ensures IT infrastructure is used in the most efficient, predictable and cost-effective manner.
Goal of capacity management: Finding the balance between density and performance.

14. Defining which Metrics to Monitor
Allocated vs. consumed resources.
CPU: The important metric to measure is CPU utilization.
Memory: Use memory consumed in most cases when evaluating memory utilization.
Memory consumed measures how much memory each VM is using on the physical host minus an memory that is shared by other VMs.
Storage: The best way to monitor storage is to look at each vmdk file from the guest OS perspective and look at utilization.

15. Identifying Allocated Resources
Allocated resources, limits and reservation info can be easily collected from vCenter or a 3rd party solution.

16. Defining your Evaluation Period
Time period: You need to decide how much data you need to analyze when computing the average or peak values to make sure that it captures your busy periods or is a good representation of your business cycles.
Priority: Many administrators will divide up their systems into high, medium and low priorities with different metrics for each group.

17. Computing Resources Consumed
The next step is to look at each resource and compute the average or peak utilization for your evaluation period.

18. Generate Recommendations
The next step is to put all the pieces together and evaluate each resource for each VM and determine if the right amount of CPU, Memory and Storage has been assigned to the VM.

19. Wasted Storage Easy to create VMs VMs are large files
Not always easy to find any files that are not being used.

20. Types of Wasted Storage
Abandoned VMs – A virtual machine file that is on your datastore but is not attached to a VM listed in vCenter or the host.
Powered off VMs
Templates Not used in 30 days or more
Snapshots
Zombie VMs – A virtual machine that is running but not being used.

21. Wasted Storage
Abandoned VMs
Powered off VMs

22. Manual or Automated?
VKernel’s Optimization Pack and Capacity Analyzer does this work for you.

23. Conclusion
The goal of virtualization is to find the balance between correctly sizing your environment while achieving maximum performance with the least amount of resources. Download a trial of VKernel’s appliances to resolve Performance bottlenecks and optimize your environment!