Mark VM disk as SSD?

[thany]

I've just realized something. So I got unRAID running on an SSD, and I've got a couple of VMs running as well. One of the VMs is a Windows 10 installation, and no problems there as it runs beautifully. However, I realized at one point that it doesn't see the installation disk as an SSD, even though unRAID hosts the disk image on the SSD. So apparently unRAID doesn't pass that information on to the guest.

 

So I guess that's a viable feature request.

 

In the mean time, is there a way to have unRAID tell the guest OS which drive is an SSD? Essentially marking a disk image as SSD? VirtualBox can do this as well, and I believe VMware too. When checking their little checkbox, the guest OS will see the disk as being solid state.

 

And why? Simple. So the guest OS doesn't go out of its way to optimize the file layout for a HDD while idling. Windpows will happily start defragging your disks if they are HDDs. For SSD it does different, much lighter optimizations. And we all know that defragging an SSD will only degrade its performance.

 

Good to know: I'm running unRAID 6.3.5, all plugins are up-to-date. Just in case this matters, the guest OS (Windows 10 in my case) is fully up-to-date as well.

[JonathanM]

 

[thany]

I don't understand your reply. I didn't ask about sparse disk files (mine are thick provisioned), and I didn't ask how to enable trim on WIndows (this happens automatically on detected SSDs).

 

So let me rephrase:

 

How can I tell the hypervisor to mark a disk as SSD so that it'll pass that on to the guest, so that the guest will detect a disk as being SSD instead of HDD?

[thany]

By now I'm running unraid 6.4.0 and I don't think there's an option to mark a virtual disk as SSD yet. And I also don't see the hypervisor passing on the "SSD or HDD" flag from the physical disks onto the VM. Any chance this might still happen?

 

Maybe I'm thinking too simplistically, but isn't this dead-easy to do? The flag is coming from the BIOS/UEFI, afaik, so if the hypervisor can read that flag, can't it just pass it on into the virtual BIOS, so that the flag ends up in the guest VM? So that the guest OS will optimize itself for SSD usage, rather than HDD usage? Or is it way more complicated?