How would we share one hard disk using shared storage and 2 proxmox hosts

[greavette]

Hello,

To preface, the reason I'm looking into this option is because we don't have a third server available to properly setup quorum, we are very small office and don't require HA. I'm also a little worried about clustering since with clustering there is only one web interface. If I lose one Host...can I be sure that my web interface will work properly. Maybe I'm being paranoid.

So here's the scoop...

We have two Proxmox Hosts running version 3.1 We have setup a shared storage NAS (using NfS and 802.3ad). Assuming only one host would ever run a VM at any onetime, is there a way to save the hard disk (.raw file) on the shared storage and have both proxmox hosts configuration files point to this shared storage for the disk. I would assign only one host to ever run the VM. In the event one host goes down we could simply start the VM on the other host and get up and running quickly again. What I'm proposing wouldn't be used for mission critical VM's.

Thoughts? How would I set this up?

Thank you.

Charles.

 

[Dragoon]

Hello,

To preface, the reason I'm looking into this option is because we don't have a third server available to properly setup quorum, we are very small office and don't require HA. I'm also a little worried about clustering since with clustering there is only one web interface. If I lose one Host...can I be sure that my web interface will work properly. Maybe I'm being paranoid.

So here's the scoop...

We have two Proxmox Hosts running version 3.1 We have setup a shared storage NAS (using NfS and 802.3ad). Assuming only one host would ever run a VM at any onetime, is there a way to save the hard disk (.raw file) on the shared storage and have both proxmox hosts configuration files point to this shared storage for the disk. I would assign only one host to ever run the VM. In the event one host goes down we could simply start the VM on the other host and get up and running quickly again. What I'm proposing wouldn't be used for mission critical VM's.

Thoughts? How would I set this up?

Thank you.

Charles.

You can have a 2 node cluster setup with a nfs share or iscsi target that is shared you don't have to use the HA features you can just migrate it when you want. You could do it out of a cluster with the iscsi target but why? If one node goes down you can access the other from the web interface just as well its not just a single master setup.

Tomislav Tom Protich
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[greavette]

Hello Dragoon,

Thank you for the reply. I have heard of two node clusters but I wasn't aware that having one would mean each Hosts Webpage would still be available. I re-read the following wiki: http://pve.proxmox.com/wiki/Proxmox_VE_2.0_Cluster. Are your suggesting I use this setup for my two node cluster (without HA)? This wiki says that with a 2 Node Cluster there is a centralized web management. But what happens when a Node Goes down? Does the other Node's IP automatically become my web management interface to use?

Also, the Beware section at the bottom of the above wiki mentions that setting up clustering is dangerous as you could have a split brain situation on your hands.

Until I can acquire a third server and setup a proper cluster with quorum I don't want to do anything to our proxmox host environment, but I do want to be able to use shared storage between 2 nodes and manually decide which Node is going to run the VM (I guess this would be live migrate but with no HA).

Any advice, steps, suggestions you or others can give to me on how to set this up would be greatly appreciated.

Thank you.

 

[Dragoon]

Hello Dragoon,

Thank you for the reply. I have heard of two node clusters but I wasn't aware that having one would mean each Hosts Webpage would still be available. I re-read the following wiki: http://pve.proxmox.com/wiki/Proxmox_VE_2.0_Cluster. Are your suggesting I use this setup for my two node cluster (without HA)? This wiki says that with a 2 Node Cluster there is a centralized web management. But what happens when a Node Goes down? Does the other Node's IP automatically become my web management interface to use?

Also, the Beware section at the bottom of the above wiki mentions that setting up clustering is dangerous as you could have a split brain situation on your hands.

Until I can acquire a third server and setup a proper cluster with quorum I don't want to do anything to our proxmox host environment, but I do want to be able to use shared storage between 2 nodes and manually decide which Node is going to run the VM (I guess this would be live migrate but with no HA).

Any advice, steps, suggestions you or others can give to me on how to set this up would be greatly appreciated.

Thank you.

Even in a cluster you can use any of your hosts node ips to access the cluster, with proxmox all nodes are masters your access is not restricted to just one node for cluster access. You could try to use the same iscsi target to different systems without being in a cluster and share the same disk storage as the iscsi target will show data proxmox should see it but this is not safe if both turn on for some reason, you have to make sure that one 1 vm is on at that time and accessing the storage then wait for access to stop before the other turns on this is slower than having 2 nodes in a cluster with just 1 target. I have had a system like this for a while with no issues and when you have another system ready just install proxmox and add to cluster.

Tomislav Tom Protich
Enterprise Vps Solutions
https://enterprisevpssolutions.com/
https://www.facebook.com/EnterpriseVpsSolutions
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http://www.linkedin.com/company/ente...-solutions-llc

 

[greavette]

Thank you for the advice Dragoon.

I unfortunately don't have a test environment to use to set up a cluster and test. Does Proxmox allow me to install Proxmox in a KVM? That way I could spin up two Proxmox KVM's and test setting up a cluster between them. Once I'm comfortable with how to do it I can move to implementing a 2 node cluster on my production servers.

Thanks.

 

[ayufan]

Thank you for the advice Dragoon.

I unfortunately don't have a test environment to use to set up a cluster and test. Does Proxmox allow me to install Proxmox in a KVM? That way I could spin up two Proxmox KVM's and test setting up a cluster between them. Once I'm comfortable with how to do it I can move to implementing a 2 node cluster on my production servers.

Thanks.

Yes, you can. But you have to use latest kernel (for ex. 3.10) not the pve-kernel. Next enable nested VT-x (enable nesting in kvm_intel or kvm_and kernel module), set CPU model of VM to host. That way you should have HW virtualization in VM. I tried it, it works.

 

[moprmac]

"manually decide which Node is going to run the VM"

Hello all,

I am trying to set up 2 dell r620 cluster with md3200 as lvm shared storage. currently have vm-100 ubtunu test kvm image and can see in lvm-vmdisks, but can't find way to start image.
So if vm-100 is running on node 1 and then kill power on node 1, how to start image on node 2?

Thanks!

Ed

 

[moprmac]

Found it finally!

If all VM disks are on shared storage, you can simply move the config files to the other node:

# mv /etc/pve/nodes/<OLDNODE>/qemu-server/<VMID>.conf /etc/pve/nodes/<NEWNODE>/qemu-server

Or you simply replace the damaged hardware, and re-add the new node using the same hostname (use --force flag for add).

Thanks,

 

[wahmed]

One of my small client uses the exact setup with 2 Proxmox Hosts and 1 FreeNAS for shared storage. It is not a HA setup. If we have to do some maintenance on the host which has all the VMs, we just simply migrate them manually to the 2nd host. We had one occasion when the host machine with VMs completely died. I did not know about the mv command you found above made by dietmar. I simply recreated all new VM and just edited the config files to point the virtual disk to the shared storage. All worked ok on first try.

 

[moprmac]

Yes I see how this works now, also I saved conf file on desktop then reinstalled proxmox, setup lvm again and copied conf file back in and vm back up.