ESXi

Hi everyone!

Am exploring ways in esxi 6. Thinking about creating 2 physical core groups (meaning not threads in a group but physical cores) ?

I am planning to have it like this:

     - in 1 core group is having 6 cores

     - in 2nd core group is having  8 cores

Is it possible or creating the group itself is not possible?.. btw, i am using the free version of esxi 6, if creating the core groups is possible then does it need a corresponding license or the free version will do.

There is no feature in vSphere that can accomplish this.

the nearest thing you can use is to restrict cetain VMs to cross over to other NUMA nodes, not sure is this is possible in the free licence though.

@MattiasN81 Thanks a lot for the reply. Very much appreciated.  Seems i need to change the way i go with it.

                          In any case, i needed to change my question to fulfil things up. Can i ask a separate question then. :smileyhappy: Lets say, i am planning to only have 2-3 VM's installed in my ESXi server. Then lock this VM's per physical CPU. Lets take below as an example:

         Assume we have 2 VM's in a esxi server with 2 socket with 12 cores all in all(HT is disabled):

                             VM1 -  would be processed by cores 1-6  (physically) ; for 1st physical cpu

                             VM2 - would be by cores 7-12 (physically); for the 2nd physical cpu

          I am looking into the physical resource rather than the virtually in this. The above would be possible right?..(i kinda read something like core scheduler or affinity or something, is this a good practice to have?). Also, is                 there a way to know which core belongs to that specific socket once operating? Or could i assume that 1st pCPU have cores 1-6 and cores 7-8 would be in the 2nd pCPU, or this thing will be be encountered in config/ along the way i am setting it up.

                           Sorry if the question may be a bit low, in any case, i only know the basics and needed supplementary on some intermediate things . I just needed to confirm if it is possible then ill do the homework on how to go and                               implement it.

Thanks again!

Well, yes.

You can use CPU affinity for this (almost) but unless you have an extreamly CPU latency sensetive application, like high speed calculations and such its never recommended to use it.

ESXi core scheduler is more than capable to handle it on its own without interference :smileyhappy:

CPU affinity is working with logical CPUs, so you can't actually lock a VM to a physical core, only logical

@MattiasN81 Thanks again. Can i conlcude here that using the restriction available in the NUMA could be best thing to do in this case rather than using the CPU affinity then.? Again, thanks for taking the time to answer. Really helps me to narrow down the area of considerations.

Both yes and no.

I depends on why you want to restrict VMs, the thing with NUMA is if you restrict a VM to only use one NUMA node and that node gets too busy while others nodes are not, then the VM cant access other nodes to use resources there and you will end up with performance problems on that VM and possible on the host itself depending on workload.

NUMA is a memory feature so if you lock a VM to one node you will lockout both CPU and RAM on the other nodes.

I only know one application that benefit fron NUMA restriction and that is SAP HANA because it runs its enitre database structure in RAM.

From licensing perspective the use of x amount of vCPUs is good enough, even from Oracle nowdays

Assuming (most probaby) the application i will be running on the VM's, will be "CPU Latency Sensitive application" then CPU affinity isn't recommended and the using of NUMA depends on the circumstances of what one wanted to do (my level of understanding and capability here doesn't equate with what i could manage as of now). So possibly i just allocate/assign vCPU and its corresponding resources on each VM. I just got my server 64Gb M with 14cores. Maximum number of VM's running is only 3. Dedicated for these 3 if you may say. As of now i may possibly let esxi core scheduler handle it as i needed further NUMA understanding and control over. Just for me to play it safe. Thank a lot for taking time to answer my questions earlier!!! :smileyhappy: