Continuous Availability (CA) allows the cluster nodes to be stretched across two fault domains, with the ability to experience up to one fault domain failure and to recover without causing cluster downtime. e. Today, vCPU count is largely determined by the manufacturer. And of course times the number of occupied sockets. 2. ) it maps to a single core. when you are running server workloads. Examples of this include a uniprocessor virtual machine with affinity to a single CPU or a two-way SMP virtual machine with affinity to only two CPUs. Total number of assigned vCPUs to a VM is calculated as:numa. I have heard best practice numbers for vSphere with newer processors at 6-10 per core. That is, the license will cover CPUs with up to 32 physical cores. Hi, That's not exactly what I said, in a given host I can assign up to 56 vCPUs to any of the hosted virtual machine, which implies as many as there are. 05-11-2015 12:52 AM. • 6:1 or greater is often going to cause a problem. This should help: (# of Processor Sockets your Server has) * (# of Cores your CPU has) = # of physical Processors (pCPU) now (# of physical processors) * (2 (because hyperthreading)) = # of vCPU'S. The hypervisor hands off tasks to the CPU and uses its own task manager to balance workload against the physical CPU. For example, if you need to configure a VM to use 2-processor sockets, each has 2 CPU cores, then the total number of logical CPUs is 2*2=4. Login to the vSphere Web Client and select the virtual machine in question. 4Ghz per core and you assign one vCPU to a VM it. This table provides the examples of socket determination based on CPU and Cores per Socket within the vSphere Web Client: The vCPU count is calculated by taking the number of processing threads per core and multiplying it by the number of cores and occupied CPU sockets. New CPUs (at least in the consumer market) will eventually likely all have the split into performance and efficient cores that Intel has started with the 12000 series. If the workloads are CPU-intensive, the vCPU-to-core ratio will need to be smaller; if the workloads are not CPU-intensive, the vCPU-to-core ratio can be larger. As for a virtual CPU (vCPU) this refers to a virtual machine’s virtual processor and can be thought of in the same vein as the CPU in a traditional physical server. When a virtual machine is scheduled, its virtual processors are scheduled to run on physical processors. A virtual processor does not necessarily have to correspond to a physical processor or to a physical CPU core. . vSphere Cluster Calculator. 6. The math is rather straight forward. Click Edit Settings on the Virtual Machine Summary Page to access the virtual machine Settings Page. it is CPU0 which is nearly 100% utilised, we do have HP agents running in the console. Press the Windows key + R to open the Run command box, then type msinfo32 and hit Enter. Ghz per Core 4. In the most simplest form, maybe think of it this way. Q1 Please clarify if following understanding of mine is correct or not: a physical CPU is namely corresponding to 1 core (embedded in a CPU socket) a VM. VMware has created a tool to identify the number of per-CPU licenses (supporting up to 32 physical cores per CPU) required for existing. For the vCPUs 2 and 3, is not needed. But the problem is we are experiencing 2vCPU is out performing 4vCPU. The maximum CPU limit for a DRS cluster is the sum of numVMCPUs * GHzPerHostCore for. The number of physical CPUs that are present in hosts is dependent on a couple factors. If workloads are CPU-intensive, the vCPU-to-core ratio will need to be smaller; if workloads are not CPU. what is the current resources usage for this dual quad core physical? is it running at 90% cpu usage or 100% cpu usage or is it more like 40% or 20% cpu usage? you might find 4 vcpu virtual would work just as well, just because a server is dual quad core doesn't always mean the machine actually uses them all, all the time, that is the. The rule of thumb when allocating CPU’s to a Virtual Machine (Best Practice) is to allocate 1 vCPU and then test the CPU utilization. e. However, this is not entirely correct, as the vCPU is made up of time slots across all available physical cores, so in general 1vCPU is actually more powerful than a single core, especially if the physical CPUs have 8 cores. The available CPU resources in the parent resource pool are insufficent for the operation. Thus, this would cause a great deal of CPU Ready because the VM would be ready to consume CPU time on 8 cores but only 4 are actually available. 0 Virtual Topology: Performance Study | Page 2. For PVUs: Multiply the number of processor cores required to license by the number of PVUs per core required for that processor family. Depending on your application workload and performance needs you can easily scale to a higher ration. In vSphere, a physical CPU (pCPU)The VMkernel Resource Manager schedules the virtual CPUs on physical CPUs, thereby managing the virtual machine’s access to physical CPU resources. For vRAM. For example, 5% of total ready reported in vSphere for an 8 vCPU virtual machine has the average of 0. . A virtual machine cannot have more virtual CPUs than the actual. The calculator is designed to be conservative and show information assuming the resources (CPU/RAM) required for the configured availability level are removed from the calculation. Not all. If you look only from the perspective of CPU performance, you should pay attention to the physical core to vCPU ratio. Active CPU is approximately equal to the ratio of the used CPU to the available CPU. A general estimation is that 1 vCPU = 1 Physical CPU Core. 5 as well. numa. You have six cores per socket. a physical CPU is namely corresponding to 1 core (embedded in a CPU socket) a VM machine (or a guest OS) recognizes/handles its CPUs always at a virtual CPU level (a virtual CPU is noted as vCPU below). CPU ready is a reliable metric to determine when or if you have truly overprovisioned your pCPU's. A typical vCPU-to-core ratio for server workloads is about 4:1—four vCPUs allocated for each available physical core. Does it mean the sum of the VM's CPU can not exceed the number of the. We install a first VM Windows Server 2019 act like DC with 2vcpu (1 socket) and a second VM for Veeam with 8vCPU (1 socket). In these cases, keep the CPU overcommitment ratio vCPU-to-pCPU less. In general we always start at the lower end of the scale (say 1 vCPU with 2 GB), monitor the running VM for a while and then possibly expand the number of vCPUs or the amount of RAm assigned. 3). Under Hardware, expand CPU to view the information about the number and type of physical processors and the number. So, for every vCPU, there's a processor thread running for each on the physical CPU. It is more akin to the share of time that the VM will recive of each clock cycle of the phyical CPU. What hyperthreading does is present each core as two logical cores to your system. All vSphere ESXi versions up to 7. In general, 1 vCPU is not equal to 1 CPU. This also degrades performance of the VM. Hello baber,. However, there are some machine types that use hyperthreading, which means that a single vCPU can be used to run two. CPU's and cores are physical, whereas the vCPU is a virtual representation/mapping for a virtual machine. 5K user OVAs" since those are 2 vCPU each. , "Windows Server 2016 is licensed under the Per Core + Client Access License (CAL) model". This gap makes it especially. Furthermore, the operator wishes to use 8 host physical CPU cores and their thread siblings for dedicated guest CPU resources. Therefore, the formula for calculating the vCPU count is: (Threads x Cores) x Physical CPU Number = Number of vCPUs. License for each processor license is flexible for up to 32 physical processing cores per CPU. ESX server provides vCPUs for VM nodes. It probably would have been better to use "each" instead of "any". For example, a dual-core processor with hyperthreading activated has two. using the above physical/virtual sizing rules for CPU, a physical server with 8 total physical cores can only host 4 of the "CUCM 7. A core is a physical unit of a CPU. 5GHz CPUs in the host, but the guest OS in the VM is consistently requesting to be scheduled for 3. The number of logical CPUs means the number of physical processor cores or two times that number if hyperthreading is enabled. Adding more vCPUs depends on the number of CPU cores and the number of timeslots, which are periods of times the. Two vCPUs will be two cores or sockets, depending on how you configure it inside the. In terms of how many vCPU can be assigned to a VM, the short answer is all of them but it is likely to cause performance issues. Select a VM, and go to the performance charts and go to advanced. You have six cores per socket. NOTE: At the time of writing the maximum vCPU limit per VM is 36 on i3 instances based on the AWS server hardware capabilities. g. e. Hi There, I would to like to know whether my math for CPU contention ratio is correct or not. coresPerSocket larger than. When HT is NOT enabled, 1 vCPU = 1 physical. %USED might depend on the frequency with which the CPU core is running. how many vCPUs are assigned to VMs Vs Cores available - going beyond 3:1 is generally touted as not ideal. This could be a lot higher or lower depending on work load and how many vCPUs you allocate to VMs. The answer is, Yes and No. But I'm fairly sure my question has been answered anyway, which is that a vCPU can't combine the total power of multiple physical CPU's (on the same host), so if the ESX host has 2 x 3. e. 5. Microsoft provides guidelines to calculate the required compute resources for a single instance of Exchange Server (as an application) so that. 4Ghz) and the virtual version now has 2 vCPUs (The ESXI host has. Recommendations for CPU sizing: 1. Therefore, to get the CPU ready % from the ms value reported by vSphere, use the formula below: CPU ready % = ( (CPU Ready summation value in ms / number of vCPUs) / (<chart update interval in seconds, default. How does VMware calculate total vCPU? 4 vCPUs per VM. For larger deployments: VMware has developed the attached PowerCLI tool that collects and consolidates information on the quantity of core licenses (with a. vSphere 7u1 is limited to 4096 vCPUs or 32x core count. That is, plan a pilot that uses 8 to 10 virtual machines per core. The calculator will then output the. g. Does this seems correct? pCPU Calculation (# Processor Sockets) X (# Cores/Processor) = # Physical Processors (pCPU) 2 x 20 = 40 pCPU vCPU Calculation (# pCPU) X (2 threads/physical processor. (16 Threads x 8 Cores) x 1 CPU = 128 vCPU. CA requires an equal number of nodes in each fault domain. For example, if a host has 128 logical CPUs, you can configure the virtual machine for 128 virtual CPUs. The default setting. pCPU or ‘physical’ CPU in its simplest terms refers to a physical CPU core i. The reservation is expressed in MHz or GHz. VMware uses the terms virtual CPU (vCPU) and physical CPU (pCPU) to distinguish between the. 7 there is no Socket or Core limit for Hosts. CPU Socket A CPU socket is a physical connector on a computer motherboard that connects to a single physical CPU. 5 Virtual Center 2. Instead of physical processor-based licensing, it was decided that core-based is licensing is a more reliable and versatile metric to calculate the computing power irrespective of the fact that. I would expect to see 1 processor with 4 cores instead of 4 x single core processors. 2 Defining an Appropriate RPO. VMware vSphere enables you to consolidate multiple workloads in the form of virtual machines on a single physical host. The percentage of time a vCPU in a run queue is waiting for the CPU scheduler to let it run on a physical CPU. . 4 vCPUs = 4 cores per socket. CPU overcommitment be less than 2:1, and ideally 1:1 for hosts servicing Exchange workloads. vCPU per core is essentially the over-subscription ratio, e. vcpu. In this example, you would need to purchase. If а CPU has more than 32 cores, you need additional CPU licenses. A vCPU, on the other hand, is a software-based variant of a computer. Essential Kits, and vSphere Scale Out. CPU Virtualization Basics. Solved: I want to get the ratio of vCPU:pCPU, For pCPU, do i need to taking in to account Hyperthread(Logical Processors)? Or just the Physical CPU Vcpu/Cpu Datacenter Sizing Calculator. 1 additional answer. Select VMs. It also may act against when several VMs with multiple vCPU has multithreaded application running, ex. Select Unlimited to specify no upper limit. refer below screen shot with 1 virtual CPU socket and changing the core to. 0GHz turbo boost. For example, "0,2-4,7" would indicate processors 0, 2, 3, 4 and 7. There is no common ratio and in fact, this line of thinking will cause you operational pain. For example, my lab has dual-socket ESXi host configurations, and each. A virtual machine cannot use more CPU cores than the number of logical processor cores on a physical machine. If you have a physical CPU running at 2. 7. A CPU is a physical chip that is installed in a computer. The calculator does not factor in the Non-Uniform Memory Access (NUMA) topology of a given hardware when making compute resource. Towards 96 vCPUs you will be well into that territory and the. vCPUs run on pCPUs and by default, virtual machines are allocated one vCPU each. VMware vSphere High Availability (HA) with Exchange Server 2016 – Overview of vSphere vMotion,. for example: you know that your cpu load is very low then you. In vSphere, a physical CPU (pCPU)The available CPU resources in the parent resource pool are insufficent for the operation. This VM runs a CPU-intensive application, and the faster the CPU - the quicker the data can be processed. The socket or sockets used by a virtual machine are dedicated to that virtual machine i. So, where it had 0 CPU ready with a pair of vCPUs, even at 80%+ use, you could have a high percentage of CPU ready when going to 4 vCPUs on the same VM, with the use. pCPU available on a host: (# of Processor Sockets) X (# of Cores) = # of Physical Processors (i. Also for increased performance allocate vCPU's in a matching format to the underlying physical CPU's. Check the VM vNUMA configuration. LOGICAL PROCESSOR = Amount of CPU's presented to the ESX Host Expert. 3% of the total CPU power of host. Some guys recommend 4 VM's to one. vCPU MHz Overhead – This setting prevents CPU oversubscription. For example, a cluster has two hosts, each of which has four CPUs that are 3 GHz each, and one virtual machine that has two virtual CPUs. 10-11-2021 01:55 AM. Solution. When sizing CPU capacity for the ESXi hosts in the management domain, consider: The requirements for the management workloads. 7GHz base clock and a 5. To start with Physical component. In other words, if there is not enough pCPU for the VM, it cannot be started. When you assign a CPU t a VM in it's settings, this is called a vCPU. 160 virtual machines. If you have a 4 vCPU VM and it never exceeds 50% usage then it would be better off with 2 vCPU's. A short spike in CPU usage or CPU ready indicates that you are making the best use of the virtual machine resources. Under Scheduling Affinity, select physical processor affinity for the virtual machine. Select the VM in question. Right-click on the virtual machine and select Edit Settings. In general, i7 is 4 and i5 is 2. In your case as you approach 48 vCPUs your host will start making more use of logical cores (Hyperthreading) and you'll be moving into "over-provisioned" territory. So if we configure 8 vCPU for a VM, there must exist at least 8 pCPU in the host. When determining how many vCPUs to assign to an Exchange Server VM, always size assuming 1 vCPU = 1 physical core. We generally use the calculation of 8 vCPU's per logical processor (on Hyper-V. On top of that, I recommend that you reserve at least one CPU core for the host operating system. This threshold cannot be overtaken because Hyper-V is. NOTE: At the time of writing, the CPU limit per VM on VMware Cloud on AWS is 36 CPUs on i3 and 96 CPUs on i3en instances based on the server hardware capabilities. there's cause for concern. Use the Number of virtual processor drop-down to lower the vCPU count by 1. When you assign a CPU t a VM in it's settings, this is called a vCPU. If you looked at ESXTOP, you would most likely notice that each HT was at 50% UTIL, and each PCPU (physical core) would be at 100% UTIL. In vSphere, administrators assign CPUs to virtual machines in order to support the workload needs of each individual virtual machine. VMs with more than one vCPU are also called symmetric multiprocessing (SMP) VMs. 7. Results: On the Physical Server, the entire application runs through its daily routine in about 90 minutes. Essjae explained it correctly in basically saying each vCPU is borrowing CPU time from the physical processors. VMware is one of the top virtualization software that allows you to create virtual machines and make the best use of your resources. On the Virtual Server, the same run takes about 30-35 minutes longer to run. Hi. Press the Ctrl + Shift + Esc keys simultaneously to open the Task Manager. Note: Remember that 1 vCPU maps onto a physical core not a physical CPU, so the virtual machine is actually getting to run on 4 cores. Sorted by: 1. First of all, you need to start with the underlying hardware, CPU and memory. 0 GHz, then one vCPU assigned to a VM will be up to 2. Your process use a specific CPU or many CPU. Since you are running 8 VMs with total 48 cores, to my knowledge you need to. The physical CPUs are owned and coordinated by the hypervisor and it divides the CPU into these. VMware vCenter. 128 vCPUs/4 vCPUs per VM = 32 VMs. The performance improvement is limited because the total computational resource is still capped by a single physical processor. Amount of usable CPU Cores for Virtual Machines after considering reservations for vSphere High Availability. , you have 2. To start with Physical component. How does VMware handle. To find a virtual machine, select a data center, folder, cluster, resource pool, or host. 2 vCPUs = 2 cores per socket. Therefore, if the vSphere administrator has created a 5:1 vCPU to pCPU ratio, each processor is supporting five vCPUs. used exceed wall clock time due to Turbo Boost, or can see. Therefore, there is no blanket statement or a simple vCPU calculator. In these cases, keep the CPU overcommitment ratio vCPU-to-pCPU less than or equal to 2:1. This threshold cannot be overtaken because Hyper-V is. André. The crucial difference in the CPU vs vCPU comparison is a technical one. Inputs: Host specification - since many software licensing schemes are linked to server CPU specification, this tool requires information about the number of servers/hosts, the number of CPUs per server, and the number of cores per CPU. Each logical proc should be treated like any other core. This guide is the 2021 edition of the best practices and recommendations for SAP HANA on VMware vSphere®. vSphere attempts to keep the VM within a NUMA node until the vCPU count of that VM exceeds the number of physical cores inside a single CPU socket of that particular host. The definition can definitely vary, for example AWS defines vCPU as:. Right-click a virtual machine in the inventory and select Edit Settings. VMware Horizon DaaS recommends you size a host based on the anticipated number of desktops for the near term. A virtual processor core (VPC) is a unit of measurement that is used to determine the licensing cost of IBM products. You're likely hitting CPU Ready alerts due to the one 16 vCPU VM being so dissimilar to the others that are hosted there. 2 Replies. Each virtual socket represents a virtualized physical CPU package and can be configured with one or more virtual cores; Virtual Core – refers to the number of cores per virtual Socket, starting with vSphere. Adding this detail for the forum users who might find it helpful. VM totalmhz = 2 vCPUs * 3000 MHz = 6000 MHz. A vCPU is a virtual central processing unit that runs on VMware, the market leader in virtualization software. 1. The limitation for the free Hypervisor is a maximum of 8 vCPUs per virtual machine. 4Ghz CPUs). 02-14-2007 05:52 AM. Virtual machines share access to CPUs and are scheduled to run by the hypervisor. Two vCPUs will be two cores or sockets, depending on how you configure it inside the guest, and will. It is possible for a VM to get 'stuck' on a single. You can press capital “ V ” for VM Only view. Make yourself familiar with the NUMA concept and the VMware implementation of vNUMA. LOGICAL PROCESSOR = Amount of CPU's presented to the ESX Host02-02-2023 02:55 AM. Also for increased performance allocate vCPU's in a matching format to the underlying physical CPU's. Then we add in the memory we need to run vCenter in a virtual machine (8GB plus 342MB), and also figure 1GB for ESX or ESXi per server. At the latest when CPU, memory or storage is used to 70% or more, you know for sure that you have to expand. A CPU is a piece of computer hardware that is commonly referred to as a “processor”. For a low latency VM without vHT, each vCPU of the VM has exclusively affinity to a thread of the physical core. A physical CPU core is controlled by the hypervisor and this is divided up into virtual CPU cores. Table 2 shows the lscpu output differences inside a VM running Red HatCPUs In a VMware environment, there are virtual CPUs (vCPUs) that are equivalent to physical CPU cores (not threads) on the host. Use the Number of virtual processor drop-down to lower the vCPU count by 1. In the above case, you can provide all cores to more than one VMs. Example: This table outlines. Sorted by: 3. These are advanced settings designed to help workloads that are cache-intensive, but not CPU intensive. If you have a physical CPU running at 2. The answer is, Yes and No. 4Ghz) and the virtual version now has 2 vCPUs (The ESXI host has 2. Total. Modern CPUs typically have multiple cores, which they can distribute processes to that need to be carried out. 1 Answer. In reality it is much more complicated (threads might not all be of the same priority, and there are also other os-related processes running), but simplified example in this case is justifiable. 5 -. More vCPUs assigned to a VM means that VM is allowed more processing time, and can eat up more total physical CPU resources. High %RDY and high %CSTP indicate an over-allocation of CPU resources – i. Virtual machines can not have more virtual CPUs than the actual number of logical CPUs on. / October 18, 2021 / Uncategorised, VMware. 2. x support a maximum of 64 vCPUs per virtual socket. For example, if the physical host contains a single 10-core CPU package, do not assigned more than 10 vCPU to the Exchange Server VM. The old 8:1 ratio still applies in a server virtualisation scenario. pCPU) The number of logical cores if hyper-threading is enabled on the host: (# of Physical Processors i. PROCESSOR = CPU. VDI Calculator. You’ll see the number of physical cores and logical processors on the bottom-right side. Under the CPU field within the Virtual Hardware tab, select the total number of vCPUs determined in Step 1. How does VMware calculate total vCPU? 4 vCPUs per VM. The number of physical cores i. ESXi Host CPU and CPU Overcommitment. g. On the Virtual Hardware tab, expand CPU, and allocate the CPU capacity for the virtual machine. First of all, you need to start with the underlying hardware, CPU and memory. The reservation “reserves” CPU resources measured in Mhz, but this has nothing to do with the CPU scheduler. 128 vCPUs/4 vCPUs per VM = 32 VMs. In fact, how many vCPU a host can assign is determined by the manufacturer. It is possible to overcommit compute resources, you could potentially have VMs running on a host that between them have more virtual processor cores than you physically have available. How VMware CPU Scheduling Works: You have one Physical Hypervisor (ESXI) with one physical CPU, 12 cores and 16 virtual machines. Use the vSphere Cluster Sizing Calculator to confirm overcommitment ratios for your cluster or to validate your design. VM totalmhz = 2 vCPUs * 3000 MHz = 6000 MHz. 4. by the number of virtual processors (vCPUs) on the server. 0 GHz, then one vCPU assigned to a VM will be up to 2. Guaranteed CPU allocation for this virtual machine. CPU configuration options: 2 vCPU (1 vCPU with 2 cores or 2 vCPU with 1 core each) or 4 vCPU (1 vCPU with 4 cores, 4 vCPU with 1 core each, or 2 vCPU with 2 cores each) 8 vCPU (1 vCPU with 8 cores, 8 vCPU with 1 core each, or 2 vCPU with 4 cores each) Number of VMs: 200: 10: Launched sessions: 200: 300: Login VSI workload:. When sizing CPU capacity for the ESXi hosts in the management domain, consider: The requirements for the management workloads. I wouldn't hesitate to run 16 or even 32 VM's with single cores on a 8 core physical machine. 5:1 or 2:1. Guaranteed CPU allocation for this virtual machine. New sizing guidelines for vRealize Operations 8. Inputs: Host specification - since the Windows Server 2022 Datacenter and Standard editions are licensed by physical core, this tool requires information about the number of servers/hosts, the number of CPUs per server, and the number of cores per CPU. 8 Cores x 8 = 64 vCPUs. CPU affinity is the same as pinning a process in Windows. There is 16MB of onboard cache. 2. The virtual machine monitor (VMM) is responsible for virtualizing the CPUs. Value, per vCPU. A Hyper-V vCPU is not a 1-to-1 mapping of a physical core. And of course times the number of occupied sockets. 1 refer to the CPU ready value. For a low latency VM without vHT, each vCPU of the VM has exclusively affinity to a thread of the physical core. 5, ESX Server 3i version 3. If this VM gets configured with a vCPU range between 11 and 20 vCPUs, the NUMA scheduler creates two NUMA clients and distributes these vCPUs evenly across the two NUMA nodes. 1. To upscale we are thinking of adding more DL385's and installed more memory on all the servers. preferHT=True – For all VMs to use hyper-threading with NUMA, add the following configuration on the ESXi Host Advance settings: numa. The number of cores and threads of an Intel processor can be found in the Intel's Technical Specifications website by searching by processor number. - Virtual CPU >= Physical CPU. If you have one socket and six cores per socket then you have 12 logical processors with hyperthreading. The vNUMA blog series by Frank. To calculate the number of vCPUs required for a particular workload, first determine the number of physical CPU cores available on the host. Then, consider the expected workload for each VM you want to host. This calculator evaluates the number of hosts in a Hyper-V cluster for the given legacy server workload and host specification. If you find this or any other answer useful please consider awarding points. I have yet to find anything conclusive; in fact, I've found a lot of information that is contradictory. Don’t create a VM larger than the total number of physical cores of your host. I wouldn't hesitate to run 16 or even 32 VM's with single cores on a 8 core physical machine. Similarly, Azure and Google also tend to match a vCPU to a hyper-thread rather than always 1:1 with an actual core. A good rule of thumb is, when sizing your VM, if the CPU utilization in the guest is on average below 20% at all times, reduce the number of vCPUs. You can configure a virtual machine with ESXi 6. vcpu. 5% of single-core cpu-time. That's all you are doing. If you need the full power of a single core for every virtual CPU, then you should avoid over-commitment. So you must calculate VM CPU RDY not each vCPU RDY. ok . 0 BEST PRACTICES GUIDEThe number of vCPU you can have highly depends on the applications you have in your machines. Answers. For ESXi 7. 5:1 or 2:1. Vcpu/Cpu Datacenter Sizing Calculator. No matter how many vCPUs you assign you are always using all of the host's CPU cores. A pCPU with 6 logical processors can support up to 72 vCPUs as long as they are in Windows 7 VMs in a VDI scenario. Use '-' for ranges and ',' to separate values. A typical vCPU-to-core ratio for server workloads is about 4:1—four vCPUs allocated for each available physical. Unfortunately I have seen this sometimes referenced as VM/core and other times. That's all you are doing. Calculating vCPU Number for a Particular Workload. To the guest OS it looks like a real CPU but on the Hypervisor (ESXi, VMware Workstation,. If not known leave as Default. If hyperthreading is enabled, each.