Hyperthreading in vSphere 4.1

[haripadmam]

Hi folks,

I'm running SAP Solution Manager application in ESXi 4.1. When they started using their application the VMs CPU utilization is directly hitting to 100% and it is consistence. But when they running the application in physical server having same configuration the utilization is around 30-40%.

SAP VM configuration is 4vCPU and 10 GB RAM.

When I googled I got information about CPU affinity. My ESXi system is enabled with hyperthreading (though this is the first time i'm seeing ESXi host enabled with hyperthreading)

So in Virtual Machine setting I made the hyperthreading setting to 'none' from 'any'. But it is of no use. Anyway tomorrow I will try disabling hyperthreading in base machine in which ESXi is running.

Have anyone resolved this issue before? Please help me with this issue.

Thank you so much...

--

hari.

[a_p_]

I don't think HyperThreading and/or CPU affinities cause the issue you see. However to find out you need to provide more info.

How  does your physical host look like (CPUs, RAM, Storage, ...) Are other VMs running on the same host and how are they configured?

Often issues are caused by CPU overutilization/overcommitment and/or storage issues.

André

[Troy_Clavell]

.... you may also want to confirm there are no limits set on this guest.

[haripadmam]

thank you for your response...

my setup includes a 5 node cluster and no VM running on the host in which this SAP VM is running .. and no such limit applied to that VM or resource pool...

My physical machine is having 64GB of RAM and 2 hexa core CPU with 12 logical core.... with hyperthreading enabled its showing 24 logical core... and storage... all VM files are in shared storage only... and in SAN logs its showing utilization max of 8 to 15% when this issue comes...

please let me know if you need any other info...

thanks,

hari.

[Troy_Clavell]

I would say, it's highly possible it's just an application issue/problem.  What process is eating up all the CPU cycles?  Are all 4 vCPU's getting equal cycles? There are no CPU %rdy issues if you run ESXTOP?

[haripadmam]

CPU utilization hits 100% and consistent when SAP application is started... when they started their application some 4-5 agents are getting created... each agent utilize cpu at average 15-20% and oracle application which utilize 30-40%... so its 100% always... all vcpu are getting utilized equally...

and reagarding ESXTOP I will run this and will attach the output tomorrow... anyway I have  checked host performance (GUI) for CPU utilization it utilizing around 30-40%..... and I can't get anyother inputs from this...I can also attach this by tomorrow...

[a_p_]

To be honest, I didn't expect this kind high end infrastructure.

So I agree with Troy, this could be a setup/configuration issue too.

For a Best Practice see e.g. http://www.vmware.com/files/pdf/downloads/partners/sap/SAP-Best-Practices-White-Paper-2009.pdf

Btw how did you provision the virtual disks? I didn't have to virtualize SAP yet, however I'd probably create eagerzeroedthick disks to prevent the block zeroing on fist access.

André

[haripadmam]

virtual disks are provisioned as vmdk files only.. from VMFS datastore...

[a_p_]

For write intensive applications a pre-zeroed virtual disk can make a huge difference.

See http://kb.vmware.com/kb/1011170 "Determining if a VMDK is zeroedthick or eagerzeroedthick". At the end of the KB article you can find the vmkfstools command which can be used to convert a virtual disk (with the VM powered off, of course)

There's also an older blog post on http://www.yellow-bricks.com/2009/11/15/performance-thin-provisioning/ mentioning this.

Stating with 4.x you can create eagerzeroedthick disks from the GUI by selecting the "Support clustering features such as Fault Tolerance" checkbox in the wizard.

André

[golddiggie]

Are you using thick or thin provisioned virtual disks/drives? If they're thin provisioned, try converting them to thick provisioned drives.

Are you running Windows 2003 or 2008 for the VM's OS?? If not 2008, did you align the disks before installing the OS and on any additional drives? If not 64 bit aligned, that could be part of the issue.

[haripadmam]

I'm using thin disks and will try to convert it to think by tomorrow and will update here with results... and VM operating system is windows 2008 EE R2 64bit...

thank you,

hari.