Hosts vs. Pools - Information Required
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xcp-ng is a distribution which runs on a bare-metal and allow us to perform virtualization. I want to know more about hosts, pools. What is the difference between these two concepts. Also what is cluster and What about HA? Where does the HA happen? b/w pools or b/w hosts?
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@irtaza9 said in Hosts vs. Pools - Information Required:
xcp-ng is a distribution which runs on a bare-metal and allow us to perform virtualization. I want to know more about hosts, pools. What is the difference between these two concepts. Also what is cluster and What about HA? Where does the HA happen? b/w pools or b/w hosts?
A single host, is a pool of 1 host. A pool can contain multiple hosts so that VMs can be live migrated from host to host (best performance with shared storage for your VMs).
HA can be achieved through a variety of options, using XOStore from the Vates team for a licensing fee. Is one such solution, but this is Sharing your Storage.
HA doesn't mandate HA Storage or Shared Storage, but it definitely helps.
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@irtaza9 said in Hosts vs. Pools - Information Required:
xcp-ng is a distribution which runs on a bare-metal and allow us to perform virtualization. I want to know more about hosts, pools. What is the difference between these two concepts. Also what is cluster and What about HA? Where does the HA happen? b/w pools or b/w hosts?
By default, when you start up XO and add your first host, that host will join a pool ( albeit the same name as the HOST you just added). You can then add more hosts to the pool to provide more redundancy or compute power.
I run a setup where different departments run different pools. I suggest taking a boo at this article as it outlines HA very clearly. One downside of HA is when you need to do an upgrade to your pool, it can be a bit of pain.
https://xcp-ng.org/blog/2024/08/22/xcp-ng-high-availability-a-guide/
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@DustinB If I add 20 hosts to a pool and create a VM in that pool, will it automatically pick the host that has sufficient resources available, such as CPU and RAM?
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Yes.
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@olivierlambert as shared earlier by @julien-f on this thread that we can only create vm on pool level and @olivierlambert said XO will automatically pick the host which has sufficient resources available for that vm. Can we manually pick the host in the pool to deploy a vm?
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@irtaza9 - you can set an affinity for a host, so that when a VM is created your VM will always try and be housed on a particular host.
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@irtaza9 You can opt to have a VM have a preferred Host Affinity, which basically means "Run here if possible" using the advanced settings while creating a VM or the Advanced settings once the VM has been created.
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Passing a PCI GPU or a USB device to a given VM basically forces this, since these cards are Host Specific and are unable to be shared across hosts in the same pool.
IIRC that is..
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@DustinB @cciecanuck Thank you.
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I think all the answers given here are providing all the info you need, right?
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O olivierlambert marked this topic as a question
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O olivierlambert has marked this topic as solved
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@olivierlambert Yes, Vates is on another level of professionalism. Wow
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Happy to help!