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What if I Turn off the Manage VM High Availability Feature and Upgrade?

  • 7 November 2022
  • 4 replies
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Hello. 

I have a question about upgrading AOS and AHV.

I understand that upgrading AOS and AHV requires restarting nodes one by one, so I need to calculate memory, CPU, storage, etc. and free up enough space.

There are customers who are currently using more than 90% of cluster memory.

cpu, there's plenty of storage.

We recommended turning off underutilized VMs to free up memory capacity, but they said it was impossible.

It also says that disabling virtual machine high availability reduces memory utilization to less than 60%.

However, it is recommended that you disable virtual machine high availability because it is a feature for recovery in the event of a host failure.
If you turn off this feature during an upgrade and an unexpected failure occurs during the process, it can be a problem, right?

In conclusion, I would appreciate it if you could tell me the correlation between upgrade and virtual machine high availability.

 

 

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Best answer by JeroenTielen 7 November 2022, 08:00

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4 replies

Userlevel 6
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If you turn off HA and do LCM with not much memory available, then some guest VMs will shut down oog they can't be migrated to another node. Best practice is to turn it on. When there is too much memory used and ha cant be turned on, the cluster is undersized. 

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Thank you very much for your reply
The upgrade operation is recommended with ha turned on
Isn't there no problem with the upgrade process if I turn off Ha to secure some memory?

What other issues will arise if the problem occurs, apart from the migration is not working properly?

Userlevel 6
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If you turn off ha then the machines are migrated on best effort. If there is no memory available to migrate the machine will be switch off. 

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Thank you for your answer.