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fcarballo
Contributor
Contributor

vCPU limit

The vCloud Director limits the number of vCPUs at 8? At the vSphere client I can choose up to 16 vCPU, but the vCloud Director just let me choose the maximum of 8 vCPUs.

My vCloud Director is backed by VMware vSphere 5 Enterprise Plus and all the organizations vDC has hardware version 8.

Regards,

Felipe Carballo

Felipe Carballo - VCP5 - VCP-Cloud
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rbudavari
Community Manager
Community Manager

Is the VM you are trying to modify still at virtual hardware version 7 ? If so it will be limited to 8 vCPUs until you upgrade it to v8.

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fcarballo
Contributor
Contributor

rbudavari,

It's hardware version 8.

Felipe Carballo - VCP5 - VCP-Cloud
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admin
Immortal
Immortal

What Guest OS?  In looking in my Lab, CentOS only allows for up to 8 vCPUs in either vCenter OR vCD.  On Windows 2008 I can pick 24 in vCenter, and I can also do so in vCD.  You should be able to assign the same number of vCPU's in vCD and vSphere as supported by the Guest OS.  "The number of vVPUS you can add to a VM depends both on the the number of CPUs on the host and the number of CPUs supported by the Guest OS" - From the UI.  You may be hitting a limitation of the guest OS, but either way you SHOULD be able to add the same number of vCPU's for that particular guest in vCD as in vSphere.

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rbudavari
Community Manager
Community Manager

Perhaps it's a Guest OS limit in that case - which OS are you using ?

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fcarballo
Contributor
Contributor

Hi Chris,

I'm using CentOS 6.x 64-bits. I don't know why, but I can only set 16 vCPUs using the vSphere Client. Like I said, the hardware version is 8.

My host has 16 Logical Processors.

Regards,

Felipe

Felipe Carballo - VCP5 - VCP-Cloud
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fcarballo
Contributor
Contributor

Hi rbuvadari,

It's CentOS 6.x 64-bits.

Felipe Carballo - VCP5 - VCP-Cloud
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lamw
Community Manager
Community Manager

This looks like an "artificial" limit that's being defined within VCD for the guestOS. In this case for CentOS 4/5/6 64bit has the configured max vCPU = 8 and this is defined during the intial installation of VCD via pre-defined SQL statments on the guesOS and some of their defult configuration including maximums.

If you take a look at the VCD appliance, under /opt/vmware/vcloud-director/db/oracle/NewInstall_Data.sql:

INSERT INTO guest_os_type (guestos_id, display_name, internal_name, family_id, is_supported, is_64bit, min_disk_gb, min_memory_mb, min_hw_version, supports_cpu_hotadd, supports_mem_hotadd, diskadapter_id, max_cpu_supported, is_personalization_enabled, is_personalization_auto, is_sysprep_supported, is_sysprep_os_packaged, cim_id, cim_version) VALUES (SEQ_GUEST_OS_TYPE.NEXTVAL, 'CentOS 4/5/6 (64-bit)', 'centos64Guest', 2, 1, 1, 16, 512, 7, 1, 1, 3, 8, 1, 0, 0, 0, 101, 0);

I suspect this was not intentional and VCD should be able to support the same maximum as vSphere. You may want to file a bug with VMware Support, but I believe this is what is causing you to only get maximum of 8 vCPU vs 16 vCPU on the same guestOS within VCD

FYI - I only recall this information as I had to go into the VCD database (not supported of course) to make a minor tweak for a trick Smiley Happy

fcarballo
Contributor
Contributor

lamw,

you are right! I took a look into the vCloud Director's database and the CentOS 64-bits is set to allow the maximum of 8 vCPU.

Felipe Carballo - VCP5 - VCP-Cloud
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rbudavari
Community Manager
Community Manager

Learn something every day Smiley Happy

lamw - I think one of us should file a bug for this (and ensure there are no other cases of misalignment between vCD and vSphere maximums).

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lamw
Community Manager
Community Manager

agreed. I actually filed it this morning.

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fcarballo
Contributor
Contributor

I opened a support ticket too.

Felipe Carballo - VCP5 - VCP-Cloud
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fcarballo
Contributor
Contributor

The VMware support instructed me to create the VM as RHEL 6 and hardware version 8. Doing so, I can choose up to 32 vCPUs.

By the way, I can only hot-add 8 vCPUs. Is it a guest OS limitation?

Regards,

Felipe Carballo

Felipe Carballo - VCP5 - VCP-Cloud
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fcarballo
Contributor
Contributor

I asked the VMware's support about the hot-add limitation I mentioned above, and the response was a little bit confusing:

What is your use case for hot adding 8VCPU's?
In the vast majority of instances, a VM should not have more than 2 VCPU's at any one time.
Adding more can actually reduce performance of the VM in question.

"A VM should not have more than 2 vCPU"?! It sounds strange to me.

Felipe Carballo - VCP5 - VCP-Cloud
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fcarballo
Contributor
Contributor

Yeah, the support is right. In the vast majority of cases, less is better. Smiley Wink

Felipe Carballo - VCP5 - VCP-Cloud
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