VMs in shared storage

[nexus2000]

Hi,

We are evaluating the proxmox hypervisor as a replacement for our currents VMware clusters.

One thing that I'm worried is regarding how the locks of the running VMs are implemented in Proxmox. In a VMware is possible to register a VM (in a shared datastore) in multiples ESXi and you can just start the VM in one of them because a lock is created in the shared datastore where the VM is, preventing another ESXi to start the same VM at the same time.

I've tested the same situation in Proxmox with a NFS datastore and there is no limitation; both VMs can run simultaneously generating a disk corruption (after a restart, both VMs, logically, cannot boot anymore).

For what I've researched the locks for the VMs in Proxmox are created in the same hypervisor (/etc/pve/qemu-server/xxxx.conf.lock). Is this correct? and if yes, are there anyway to change that behaviour?

Thanks.

 

[bbgeek17]

If I understand you correctly, you have independent multiple ESX (clusters?) sharing one NFS datastore and your rely on the exclusive file lock placed by the ESX to prevent two VMs pointing to same disk from running concurrently? If so, thats quiet an odd workflow. It may have worked for you but locks can be released and/or lost and then there is nothing standing in the way of data corruption.

AFAIK PVE does not have logic in the product to place an extra lock along side the virtual disk that another independent PVE can check for, before grabbing the disk for itself. I imaging that adding such functionality for an edge case is unlikely.

There is already a robust arbitration mechanism in PVE that allows only one VM to own the disk - PVE Cluster.

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Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[nexus2000]

Yes, multiples ESXi without a cluster. I know is a odd workflow (and is not what we used, just a test) but just wanted to know if I was missing something in the Proxmox configuration or just the way that Proxmox works.

Thanks.

 

[bbgeek17]

wanted to know if I was missing something in the Proxmox configuration or just the way that Proxmox works.

You have not missed anything - its an unsupported workflow and there is no bumper in place for someone to corrupt their data should they attempt to do it.

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Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox