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Sherlock
Asked: 2020-04-15 07:21:31 +0800 CST

XenServer (Citrix) Management Network Interruption

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We have an OOB/management network we use to loginto storage, hosts etc. We're using VLANs to separate out storage, from hosts, to camera's etc.

We would like to replace this switch with a new one using the previous config but we're wondering what processes, if any, does Xen have running that would utilize the OOB network such as pool communication?

If we take out the current OOB router to replace it, and Xen hosts do not have access to OOB network for a period of time (say 5 minutes?) this is going to cause an issue with Xen?

xen networking citrix xenserver ubiquiti-edgerouter

1 Answers

  1. Best Answer

    The heartbeat via the OOB is important in case you have self-fence setupped for a restart.

    Unplugging it would cause the server to self-fence, which by default mean all your servers/hosts would reboot.

    Make sure your self-fence is configured ok, or just disable HA for the time you do the operation.

    Servers will self-fence (that is, power off and restart) in the event of any heartbeat failure unless any of the following hold true:

    -The storage heartbeat is present for all servers but the network has partitioned (so that there are now two groups of servers). In this case, all of the servers that are members of the largest network partition stay running, and the servers in the smaller network partition self-fence. The assumption here is that the network outage has isolated the VMs, and they ought to be restarted on a server with working networking. If the network partitions are exactly the same size, then only one of them will self-fence according to a stable selection function.
    - If the storage heartbeat goes away but the network heartbeat remains, then the servers check to see if they can see all other servers over the network. If this condition holds true, then the servers remain running on the assumption that the storage heartbeat server has gone away. This doesn't compromise VM safety, but any network glitches will result in fencing, since that would mean both heartbeats have disappeared.

    https://support.citrix.com/article/CTX217735

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