On Tue, May 19, 2020 at 10:18 AM <souvaliotimaria@mail.com> wrote:

Hello everyone,

I have an oVirt 4.3.2.5 hyperconverged 3 node production environment and we want to add some RAM to it.

Can I upgrade the RAM without my users noticing any disruptions and keep the VMs running?

The way I thought I should do it was to migrate any running VMs to the other nodes, then set one node in maintenance mode, shut it down, place the new memory, bring it back up, remove it from maintenance mode and see how the installation reacts and repeat for the other two nodes. Is this correct or should I follow another way?

Will there be a problem during the time when the nodes will not be identical in their resources?

Thank you for your time,
Souvalioti Maria

Hi,

as far as storage is concerned, are you using arbiter on one of the nodes (keeping only metadata on it and so only 2 copies of data) or a full copy on all of them?

See here for more info and details:

https://www.ovirt.org/develop/release-management/features/gluster/gluster-arbiter-volume.html

If you are using arbiter on one node, when you are updating one of the other two nodes, you will have only 1 copy of data active, so take care of it.

Also, if your VMs make heavy I/O, keep in mind that when rejoining one "data" node it could take time for it to align the data, depending on what has been processed during its downtime, so wait for all healing operations to have completed, before proceeding with the next data node.

You can see healing information on a node for its volumes with the command

gluster volume heal volume_name info

More info here:

https://docs.gluster.org/en/latest/Administrator%20Guide/Managing%20Volumes/#triggering-self-heal-on-replicate

Not verified on the field, but in theory oVirt should run those commands under the curtains for you and not let you put a host into maintenance if there are healing operations that need to be completed.

See here:

https://www.ovirt.org/develop/release-management/features/gluster/gluster-self-heal-monitoring.html

HIH,

Gianluca