Questions: Placing a new VM in a suitable pool/How is a host chosen ?

skurtin

Hello,

I was tasked to automate some processes involving XO. After gaining insight into the API I am now stuck with the question how to choose a suitable pool for a new VM. We have multiple pools, mainly for separation purpose. Using the WebUI I can choose a pool based on my gut feeling, but then the host is chosen automagically. Therefor my both questions:
What would be a good method to pick a pool for a new VM ? Would checking the RAM allocation be enough ? Would it be a good way to gather all metrics from all hosts and sum them up ?
How is a host inside a pool chosen ? What factors are taken into account ? I have no insight into the process/algo.

Thank you in advance.
Best regards.

olivierlambert

To pick a pool: it's up to you to decide, depending on available pool storage capacity, speed. Same for compute and network. It's very very specific to your own needs, there's no universal rules.
Host selection for a VM: it's not decided by XO but by XAPI (except if you specifically ask to boot on a host). IIRC, it's a mix of load and memory available, but if you want to dig further, it should be written in the XAPI code somewhere