VM Replication - Two-way?

[mharald]

Hello community,

Love Proxmox. So much fun to work with!

I have a few VMs with local ZFS storage and a 2-Node (still figuring out where to install the 3rd) setup.

I setup replication for a VM from node A (where it is currently running) to node B.

Does a replication from node B to node A make sense? Would it ruin the VM? What are the consequences?

I have not found any documentation explaining this (nor thread).

Would anybody be so kind and explain this to me?

Thank you and regards,

Harald

 

[ermanishchawla]

3 nodes are required for using ha-manager which will automatically migrate the vm on failure.
ZFS replication is not very useful to achieve high availability, it just reduces time in bringing up the node in case of failure
high availability with zero downtime is achieved through 3 node setup in a cluster

 

[spirit]

you can have replication in both way at the same time.
proxmox HA reverse the replication for you in case of failover

 

[mharald]

you can have replication in both way at the same time.
proxmox HA reverse the replication for you in case of failover

Thank you for your reply!

I still have a few gaps to fill regarding replication. My question has the following background:

15 Minute replication scenario
=========================
If node A replicates with node B at 1300 hs. What happens when node B tries to replicate back to node A at 1305 hs?

Do you know exactly how this works? Are replications from node B to node A deactivated as long as the VM is running on node A?

Regards,

Harald

 

[mharald]

3 nodes are required for using ha-manager which will automatically migrate the vm on failure.
ZFS replication is not very useful to achieve high availability, it just reduces time in bringing up the node in case of failure
high availability with zero downtime is achieved through 3 node setup in a cluster

Thank you. I am aware of the HA requirements. This is no production environment.

Regards,

Harald

 

[mbgevers]

3 nodes are required for using ha-manager which will automatically migrate the vm on failure.
ZFS replication is not very useful to achieve high availability, it just reduces time in bringing up the node in case of failure
high availability with zero downtime is achieved through 3 node setup in a cluster

Sorry to say, but even this is an old post, your information is wrong. HA requires a quorum like in votings, so installing a qdevice is enough, see https://pve.proxmox.com/wiki/Cluster_Manager



at supported setups they write:



We support QDevices for clusters with an even number of nodes and recommend it for 2 node clusters, if they should provide higher availability. For clusters with an odd node count, we currently discourage the use of QDevices. The reason for this is the difference in the votes which the QDevice provides for each cluster type. Even numbered clusters get a single additional vote, which only increases availability, because if the QDevice itself fails, you are in the same position as with no QDevice at all.