Dedicated host related questions

Mr. B 26 Reputation points
2021-04-07T04:14:41.583+00:00

We are evaluating dedicated hosts and have couple of questions

  1. Default quota for dedicated host is 3000 per region per subscription. Can this quota be increased? if so to what limit.
  2. Dedicated hosts consume quota from "Dedicated Hosts vCores" as well as vCores of SKU family. Does deploying a VMSS on these dedicated hosts require it's own quota?
  3. Once the VMSS is deployed on say host group with 2 hosts and later if the host group is expanded to 4 hosts does VMs in VMSS rebalance? If they don't is there an API to move the VM in a VMSS to different host in the host group?
  4. Is the placement logic of VMs in VMSS on dedicated hosts documented any where?
  5. Decrease in number of hosts in host group does not seem to work when deploying via ARM template even though there are no VMs on these hosts.
Azure Dedicated Host
Azure Dedicated Host
An Azure service that provides a dedicated physical server to host Azure virtual machines for Windows and Linux.
48 questions
Azure Virtual Machine Scale Sets
Azure Virtual Machine Scale Sets
Azure compute resources that are used to create and manage groups of heterogeneous load-balanced virtual machines.
352 questions
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  1. shiva patpi 13,141 Reputation points Microsoft Employee
    2021-04-10T19:46:39.49+00:00

    Hello @Mr. B ,
    Thanks for your query ! Here are the answers

    Default quota for dedicated host is 3000 per region per subscription. Can this quota be increased? if so to what limit.
    It can be increased , there will definitely be maximum soft limits

    Dedicated hosts consume quota from "Dedicated Hosts vCores" as well as vCores of SKU family. Does deploying a VMSS on these dedicated hosts require it's own quota?
    No additional quota is needed separately for VMSS

    Is the placement logic of VMs in VMSS on dedicated hosts documented any where?

    • Have a look at the video with a detailed explanation https://azure.microsoft.com/en-us/services/virtual-machines/dedicated-host/#features , it will answer most of your queries
    • Basically VMSS as you know it's a group of VMs , when you assign the VMSS to a dedicated host then each VM with-in a scale set will be assigned to individual dedicated host .
    • You have the option of Explicit assignment or an automatic placement (Azure platform will pick the dedicated host for you) . For this to work , you need to enable Automatic placement at host group level and point the VMSS to that particular host group.
    • Video all gives a detailed list of additional VM sizes which are supported as a part of dedicated host deployments
    • Make a note of High Availability options with Zonal placement and the working mechanisms w.r.t Fault Domains
    • Once you create the VMSS with automatic placement , you can see it which VM is assigned to which Host etc.

    Take a look at the general questions w.r.t Azure Dedicated host and basic concepts

    Kindly let us know if you have additional questions, if above helps - please make sure to "Upvote and Accept the answer"

    Regards,
    Shiva.

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