How do you handle Proxmox clusters when you only have 1 or 2 servers?

I technically have 3 servers but I keep one offline because I don’t need it 24/7 most point wasting power on a server I don’t need.

I believe I read somewhere that you can force Proxmox it to a lower number but it isn’t recommended. Has anyone done this and if so have you run into any issues with this?

My main issue is I want my VM to start no matter what. For example I had a power outage. When the servers came back online instead of starting they waited for the quorum number to reach 3. (it will never reach 3 because the third server wasn’t turn on.) so they just waited forever until I got home and ran

pvecm expected 2

  • towerful@beehaw.org
    2·
    1 year ago

    I have 2 nodes and a raspberry pi as a qdevice.
    I can still power off 1 node (so I have 1 node and an rpi) if I want to.
    To avoid split brain, if a node can see the qdevice then it is part of the cluster. If it can’t, then the node is in a degraded state.
    Qdevices are only recommended in some scenarios, which I can’t remember off the top of my head.

    With 2 nodes, you can’t set up CEPH cluster (well, I don’t think you can).
    But you can set up High Availability, and use ZFS snapshot replication on a 5 minute interval (so, if your VMs host goes down, the other host can start it with a potentially outdated snapshot).

    This worked for my project as I could have a few stateless services that could bounce between nodes, and I had a postgres VM with streaming replication (postgres not ZFS) and failover. Which lead to a decently fault tolerant setup.

  • Zoë@lemmy.mlM
    1·
    1 year ago

    Please do add a tag to your post as stated on the sublemmy sidebar! Thank you. :)

  • deejay4am@lemmy.world
    1·
    1 year ago

    You can use a small device like a Raspberry Pi as a Qdevice to be the third vote in quorum. It doesn’t have to be a full Proxmox server.

  • Irisos@lemmy.umainfo.live
    1·
    1 year ago

    If you are not using any HA feature and only put servers into the same cluster for ease of management.

    You could use the same command but with a value of 1.

    The reason quorum exist is to prevent any server to arbitrarily failover VMs when it believes the other node(s) is down and create a split brain situation.

    But if that risk does not exist to begin with, so do the quorum.

  • PrivateButts@geddit.social
    1·
    1 year ago

    You’ll need a QDevice to keep consensus. That wiki article will cover how to set it up and some drawbacks to QDevices. You should be able to run it on a low-power device like a Pi to keep the cluster going.

  • MangoPenguin@lemmy.blahaj.zone
    1·
    1 year ago

    AFAIK forcing it to a lower number is fine if you’re not doing HA. I remember reading something along those lines on a forum, but I could be remembering wrong.

    If you’re not using Ceph or HA, then I don’t think there would be any negative effects from not having all the servers in the cluster ready.

  • Dougie@lemmy.dougiverse.io
    0·
    1 year ago

    I haven’t tested this at all, it’s just popped into my head, but, could you create a VM on one of the nodes and join that to the cluster?

    If it does work, I wouldn’t recommend it. But I’d be curious to see if that would work.

    • Catsrules@lemmy.mlOP
      1·
      1 year ago

      That leads to a chicken and egg situation. The Proxmox cluster can’t turn on VM because the VM isn’t on to be the third node in the cluster number :)