Making a cluster

[TIENDER]

Hi,

Recently i'm running proxmox on a single server.
Things like home-automation, vpn server, NAS, surveillance, and some network are on this server.

As the server is a singe-point of failure i want to make it more reliable. But before i order all of the hardware, i want to make sure its going to work

Actually i want to build an exact same server.

Asus p11c-i
i3 8100 (New server i3-9100)
2x crucial mx500 SDD
2x seagate 4TB HDD
32GB Ram (Non ECC but i want to upgrade to ECC)

I´ve read that you nead 3 nodes for HA, but i dont want to build another expensive system. Can i achieve this with a raspberry pi or something?

Does the other server automaticly take over the VM's of the crashed server?
I think the data on the storages in both servers will be exactly the same, Is that right?

Do i need to have:

Server 1:
SSD in mirror
HHD in mirror

Server 2:
SSD in mirror
HHD in mirror


Or is there another option, cause in this case i've got 4x 500GB=2TB SSD but can use only 500GB

 

[aaron]

Can i achieve this with a raspberry pi or something?

Have a look at the QDevice mechanism to get a 3rd vote into the cluster.

Does the other server automaticly take over the VM's of the crashed server?
I think the data on the storages in both servers will be exactly the same, Is that right?

If you enable HA. But for that you need either a shared storage or use the VM replication to have a somewhat current disk image on the failover node. Depending on the replication interval, you might have more or less data loss.

 

[TIENDER]

Thanks for you reply.

I've read the article about Qdevice mechanism. It would be a good solution to my 2 node cluster.

The Corosync Quorum Device (QDevice) is a daemon which runs on each cluster node.

This can be done safely as the external device can see all nodes and thus choose only one set of nodes to give its vote.

But do i need to install this on an external device(like a rbpi), or do is install it on the 2 servers where it acts as an external device?



I don't have a shared storage. (The storage/NAS is an VM in proxmox), so iam going to use VM replication.

 

[aaron]

But do i need to install this on an external device(like a rbpi), or do is install it on the 2 servers where it acts as an external device?

You need to install the corosync-qnetd service on the external (rpi) machine and the corosync-qdevice on the PVE nodes.

I don't have a shared storage. (The storage/NAS is an VM in proxmox), so iam going to use VM replication.

Make sure to have the same ZFS storage on both nodes for this to work.

 

[TIENDER]

Thanks for you reply, The quorum setup is clear now.
Still got some harware questions.

If you got a shared storage on another device, and that storage device fails. Does that mean that both of the nodes also fail? Or is it possible to share storage within de two nodes(so without an extra device for storage)

For adding a second node i'm a bit confused on how to set up the SSD and HDD's

Node1:
2x SSD 500GB in raid mirror
2x HDD 4TB in raid mirror (NAS)
2x HDD 2TB in raid mirror (Surveillance)

Node 2:
2x SSD 500GB in raid mirror
2x HDD 4TB in raid mirror (NAS)
2x HDD 2TB in raid mirror (Surveillance)

Is this the right way to assemble the nodes? Cause in this case i've got 4x SSD/HDD but can only use the capacity of 1 SSD/HDD

Or can i just go with 1 disk on each node? Then it wil not be RAID mirror, but i've got the redundancy of the two nodes.