CPU Resource Determination Advice Needed

[TCLiven]

Hello -

Environment = ESXi 4.0

Cluster 1 = 13 hosts/55 guests

Cluster 2 = 7 hosts/38 guests

Cluster 1 has 2 resource pools created, 1 of the resource pools contains 2 guests that constantly are starving for more CPU, spikes several times a day and stays spiked for 30+ minutes.

Both of the guests are running on 1 CPU.  How can I determine if I need to add a CPU to the guest or change the resource pool settings?

Currently the CPU resources in the resource pool settings are:

Shares: Normal (4000)

Reservation: 0 MHz

Expandable Reservation is checked

Limit: 60000 MHz

Unlimited is unchecked.

The resource pool houses 13 guests in addition to these 2 that constantly alarm as to needing more CPU (averages between 70000 - 90000).  The other guests very rarely and if so, spike and then goes down, complains of needing more.

My first inclination is to bump up the reserve to 80000 however I noticed that the systems are only on one CPU and thought maybe adding a second would help more.  The guests are document cyclers, so they are sent batch jobs through out the day of hundreds/thousands of documents and the server sorts the documents and places them in specific functional areas for the user community.

Any advice would be greatly appreciated since I am still pretty green on how the Resource Pools work.  Thank you in advance.

[BobD01]

Can I ask why you need to use Resource Pools at all?  You don't always need RP's.  I'm not suggesting you should NOT use them but you shouldn't feel you have to use them!  If you let me know what you are trying to achieve with RPs I may be able to assist.

cheers

Bob

[TCLiven]

Hi Bob -

Thank you for the response.  I did not setup the Resource Pool, the previous VM admin did.  What I think he was trying to do was be able to report on what the 'core' application servers in our environment takes up in our VM resources.  This is asked of us quite often and is used to justify new hosts when a request comes in for a cpu or memory intensive application.  Thank you for your help.

[BobD01]

I wouldn't use reservations for this scenario.  The CPU intensive VMs - do you know if the app is truely multi-threaded?  If so and if the CPU Ready counter is high (i.e. it's  waiting for CPU cycles) it may well be worth adding a second vCPU.

[idle-jam]

have a read at the below URL. it gives you more understanding on resource management.

http://www.vmware.com/pdf/vsphere4/r41/vsp_41_resource_mgmt.pdf

[MauroBonder · Accepted solution]

I would recommend you read the VMware Resource Management Guide here www.vmware.com/pdf/vsphere4/r40/vsp_40_resource_mgmt.pdf

It's  important to thorougly understand those settings and how it works and  limitation to be effective.  If you do not know and implemented resource  pool, you will ended up shooting your foot, but remember that resources  allocation for memory reservation is not sharable and not reclaimable.

http://frankdenneman.nl/2010/05/resource-pools-memory-reservations/ great post and explanation.