Proxmox 6 with cache=writeback and modern kernels VMs

[DANILO MONTAGNA]

Hi,

I would like your advises regarding enabling or not writeback cache on guest VMs..

We only use modern OSEs like, Centos 7, Centos 8, Ubuntu 16, WIndows 16/19...

What are your recommendations with writeback cache enabled on proxmox guests?

With these modern kernels, will be any chance of a guest OS corruption with writeback enabled after a completely power failure from proxmox node?

Our environment utilizes shared storages with BBU enabled on storage controllers.. the guest virtual disks are stored over these iscsi storages using Shared LVM filesystem.

Proxmox nodes has dual power supply, UPS, Power Generator etc.. but a crash on a node can always happen!!! and since it's a production environment with hundred of VMs, I'm concerned about enabling it or not, because the performance increase inside the VMs has a huge difference!!!

 

[Dominic]

Have you found an answer already? There is some information about this in the Wiki.

 

[DANILO MONTAGNA]

Have you found an answer already? There is some information about this in the Wiki.

Yes, I read this, but there is no answer for my doubt.. not quite clear about what scenarios can we use or not writeback enabled!!!

 

[guletz]

Our environment utilizes shared storages with BBU enabled on storage controllers.. the guest virtual disks are stored over these iscsi storages using Shared LVM filesystem.

Yes, it is a good chance to lose some data using write-back if you lose the power+the network switches(iscsi) + bbu.

 

[DANILO MONTAGNA]

if you lose the power+the network switches(iscsi) + bbu

If I lose all together at same time or any single of it will lose data too ?

 

[guletz]

... all at the same time.