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CUC - VM Insufficient CPU Resource to start VM


I am running into an issue when trying to stand up a new CUC instance.  We are trying to migrate off of old hardware in order to upgrade from our existing 10.5 to 12.5, which I will outline more of below.  As the title states we are bumping our heads when trying to start the VM for CUC 12.5.2.  I know that the issue is with the VM reservation.

Our existing infrastructure consists of two UCS-C24-M3S with 2x Intel Xeon E5-2640 @ 2.5GHz and 64GB of RAM running ESXI 5.5.  The original versions of CUC/CUCM that were stood up were 10.5.1 using the CUC_10.5_vmv8_v1.5.ova and CUCM_10.5_vmv8_v1.8.ova.  I can see that this version of the OVA for CUC 10.5 set the CPU reservation at 4998MHz.  This is within the range of 2500x2 cpus of 5000MHz the system can provide.

We are trying to move to our vCenter cluster running 4 UCS-B200-M5 with 2x Intel Xeon Silver 4110 @ 2.10GHz and 256GB of RAM.  I am trying to deploy the 10.5.2 CUC OVAs for ESXI 5.5+.  These newer OVAs set the CPU reservation at 5060MHZ which is out of the range of the 2100x2 cpus of 4200MHz. 

Even if I were to try the 10.5.1 OVAs we would not have enough CPU capacity to meet the reservation requirements.  I have read some of the caveat pages, but I can't see anything that would help me.  Is our only path forward to upgrade hardware in our new UCS chassis?  Either by adding new blades or upgrading the existing with new CPUs?  The cluster also consists of several older M3 blades with Intel Xeon E5-2650 @ 2GHz, which also not satisfy the reservation requirements of the OVA.  I know I cannot just change the reservation and expect it to still be in support by Cisco.  However it seems that CUCM/UCCX reservations would be okay with current hardware and only CUC that we bump our heads with.  Thank you for all of your assistance.


3 Replies 3

Newer and faster CPU's sometimes don't run at as high a clock speed as older CPU's. That means you could adjust the CPU reservation MHZ down to what would be provided by 2 CPU's on the newer server. You should look up all the compatibility guides too. There is almost certainly going to be additional RAM required for 12.5 VM's. You can always get an idea of what the newer requirements are if you build new VM's for the appropriate version and see what CPU, memory are configured as well as any reservations.

Edit: build new 12.5 VM's to see what the requirements will be in the end state. If you are using B series blades, that likely means you have external storage of some sort. Make sure that meets the criteria including the IOPS.


Hello Anthony,

Which SU of 12.5 version you are targeting? How many users you are designing in your CUC?

You must consider Physical CPU base frequency for each use case:



Try this: I found in my lab that having the CPU Latency Sensitivity set at "High", which is the default setting, was preventing me from installing CUC 12.5, generating the "Insufficient CPU Resource" error. After selecting the OVA, but before installation, change that setting to Normal (I think that was the setting) I was able to install CUC.

VM Options Tab > Advanced and then find the Latency Sensitivity setting.


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