How is SMART handled on passthrough?

[terry5008]

If I'm virtualizing a TrueNAS server(Core or Scale) and I'm passing through hard drives rather than an entire controller, which software handles SMART? Is it Proxmox or TrueNAS? And if it is Proxmox, then in the event of a drive failure, how would TrueNAS know? And if this is a problem, would passing the entire controller through be a better option?

 

[leesteken]

If I'm virtualizing a TrueNAS server(Core or Scale) and I'm passing through hard drives rather than an entire controller, which software handles SMART? Is it Proxmox or TrueNAS?

Proxmox, SMART is not passed or emulated to the VM.

And if it is Proxmox, then in the event of a drive failure, how would TrueNAS know?

Drive failure and SMART are separate things. It's possible the VM would not start because the drive is missing. It's possible that IO errors are not passed directly but the VM would get some kind of error when doing I/O. It's also possible that data corruption goes unnoticed.

And if this is a problem, would passing the entire controller through be a better option?

Is it a problem for you? PCIe passthrough comes with its own set of caveats and potential problems.
Lots of threads of this forum about SMART, disk passthrough, controller passthrough, pros and cons.