difference: pvecm and ha-manager

[proxmox_larry]

Hey guys,

I understand that we use pvecm to create and manage a cluster.
Furthermore the purpose of the ha-manager is to do automatic failovers etc.

But what is the main Clustermanager in Proxmox? How do pvecm and ha-manger (lrm and crm) work together?

Thanks!

 

[dietmar]

corosync and pmxcfs

https://en.wikipedia.org/wiki/Corosync_Cluster_Engine

https://pve.proxmox.com/wiki/Proxmox_Cluster_File_System_(pmxcfs)

 

[proxmox_larry]

That's not really the answer to my question

 

[dietmar]

That's not really the answer to my question

Then I do not understand the question ...

 

[proxmox_larry]

What is the Clustermanager in Proxmox? pvecm or ha-manager?

 

[dietmar]

Please can you define the term "Clustermanager"?

 

[proxmox_larry]

Your wiki defines pvecm as cluster manager: https://pve.proxmox.com/wiki/Cluster_Manager.
This magazine defines ha manager as cluster manager: http://www.admin-magazine.com/Archive/2017/42/Proxmox-virtualization-manager

That's the reason why I'm a little bit confused.
Neither there is real scheme, which expresses the relationship between this terms..

 

[tom]

The primary source of information is our reference documentation on:

https://pve.proxmox.com/pve-docs/

 

[proxmox_larry]

Thank you Tom, but I know this document already and didn't found an answer to my question there ...

 

[tom]

my question

Maybe you need to ask a bit more detailed.

A cluster and HA is probably a bit complex for beginners, so just let us know which detail you miss.

 

[narrateourale]

AFAIU the pmxcfs in combination with corosync provide decision making and distribution across the cluster nodes. Stuff like which version of a config file is the accepted one. The pvecm tool manages this aspect.

The ha manager and the associated services lrm and crm come into the picture as soon as you actually need HA and handle that part of the cluster operation on top of the the pmxcfs/corosync part.

So from my high point understanding this is not a question which one is the real cluster manager but what features of a cluster do you need. A cluster definitely needs pmxcfs and corosync but not necessarily HA functionality.

 

[dietmar]

Right. The important point here is that there is no central unit making all decisions. Proxmox cluster is a distributed system, and there is no single point of failure.

 

[proxmox_larry]

AFAIU the pmxcfs in combination with corosync provide decision making and distribution across the cluster nodes. Stuff like which version of a config file is the accepted one. The pvecm tool manages this aspect.

The ha manager and the associated services lrm and crm come into the picture as soon as you actually need HA and handle that part of the cluster operation on top of the the pmxcfs/corosync part.

So from my high point understanding this is not a question which one is the real cluster manager but what features of a cluster do you need. A cluster definitely needs pmxcfs and corosync but not necessarily HA functionality.

I really like your explanation and think that I understand the difference between both.
Also thank you @dietmar @tom