Virtualized Truenas Scale, with passed through physical disks (no HBA) is it possible?

[titust1]

Hi everyone,
Proxmox is capable to pass through disks to a VM as a virtio drive.
Can I passthrough all my 4 HDDs to the Truenas VM, and then create a Raidz with them? I don't see why not?
The only impediment I could see is the fact that virtio drives don't have serial numbers and Truenas does not like this.
Most people suggest to use an HBA (like an LSI) and passthrough the HBA to the VM instead.
Isn't this almost the same thing?
Have you guys tried this?
Thanks a lot,
Experts opinion highly appreciated

 

[Samuel Tai]

It's not the same thing. This has been tried multiple times, and almost, almost works. It will appear to work in the beginning, but you will gradually find instances where it doesn't, and will end with losing data.

 

[sretalla]

Can I passthrough all my 4 HDDs to the Truenas VM, and then create a Raidz with them?

We can't stop you and it will "work", so yes, you can do that.

We recommend that you don't as you're likely to lose your data if you run that way.

I don't see why not?

As mentioned, you can, we're just recommending that you won't like the result if you do (in the long term... even if it appears to work for a while first).

The only impediment I could see is the fact that virtio drives don't have serial numbers and Truenas does not like this.

No. That's not it at all... the virtio drivers effectively act like a RAID controller... this post explains why that's bad.

What's all the noise about HBA's, and why can't I use a RAID controller?

This is relevant to FreeNAS and TrueNAS CORE. Some parts of it might also be relevant to Scale, but I don't really know how reliable the Linux drivers are. 1) An HBA is a Host Bus Adapter. This is a controller that allows SAS and SATA devices to be attached to, and communicate directly with...

www.truenas.com

Most people suggest to use an HBA (like an LSI) and passthrough the HBA to the VM instead.
Isn't this almost the same thing?

As mentioned already by @Samuel Tai it's not at all the same (see the thread I linked above).

Have you guys tried this?

I have done it in VMs, but only for testing and never with data I would be upset to lose.

The forum is littered with examples of people finding out the hard way that you shouldn't do it. It's usually too late for saving their data by the time we get involved.

 

[titust1]

We recommend that you don't as you're likely to lose your data if you run that way

I got it, thanks. and that’s why I kindly asked, to get an expert advise. I‘ve already did try it myself too, to test it, and as you said it works, but I don’t want to risk putting my data there. Thanks again

the virtio drivers effectively act like a RAID controller... this post explains why that's bad.

I’ve never intended to use a Raid controller.
I ordered an LSI HBA with the IT firmware and I’ll pass this through in Proxmox to the Truenas VM.
Then in Truenas I’ll create the Raidz with the HBA provided drives
I hope that’s OK…..

 

[sretalla]

I’ve never intended to use a Raid controller.

Clear enough, but it works like one anyway, putting a cache/buffer between TrueNAS and the physical disk (just like a RAID controller does in "passthrough/legacy/JBOD" mode).

I ordered an LSI HBA with the IT firmware and I’ll pass this through in Proxmox to the Truenas VM.
Then in Truenas I’ll create the Raidz with the HBA provided drives
I hope that’s OK…..

Sounds like the kind of plan that won't lose your data...

Thread '"Absolutely must virtualize FreeNAS!" ... a guide to not completely losing your data.'

 

[danb35]

I ordered an LSI HBA with the IT firmware and I’ll pass this through in Proxmox to the Truenas VM.

Sounds like the safest course of action possible with Proxmox. Be aware that Proxmox' PCI passthrough isn't very mature compared to, e.g., ESXi.