VM backup, snapshot without virtual disk

[mkaszas]

Hi Guys,

So during the weekend I finally setup my OSX ( Macinabox rulez! ) and Windows 10 VMs with GPU passthrough ( Sapphire RX 580 Nitro+ for OSX Big Sur and GTX 1070 for Windows. For Unraid I am using the Intel integrated graphics ).
For the OSX VM I used an NVME drive directly through VFIO ( for performance reasons ) so there is no virtual disk. 
How can I regularly back it up? Whats the best practice so if something happens I can recover it easily? 
Or should I re-create the VM using a virtual disk and use an NVME for caching? ( Would it provide the same or really close performance? )
I have two 4 TB parity drives and one 1 TB SSD for data drive currently. But will most likely add to these.
 
Thanks in advance!

Best Wishes,
Matt

[ghost82]

1 hour ago, mkaszas said:

How can I regularly back it up? Whats the best practice so if something happens I can recover it easily? 

Since you passed through the nvme controller+disk you do backup as bare metal installations.

I see two options:

1. dd (https://man7.org/linux/man-pages/man1/dd.1.html) from unraid terminal to clone the full nvme disk to an image which can be restored on a disk of equal size or bigger

2. applications from within mac os: superduper and carbon copy cloner are paid applications which work good, which allow you to have bootable dmg backups

 

You can use the above methods regularly, on os updates, and use some other mac os applications to sync your files/folders, I'm using the freeware Freefilesync and I'm very satisfied.

 

1 hour ago, mkaszas said:

Or should I re-create the VM using a virtual disk and use an NVME for caching? ( Would it provide the same or really close performance? )

I don't have an nvme, but I would suggest to leave it as it is, i.e. nvme passthrough. I was using a vdisk on a ssd, then I chose to passthrough the sata controller with the same ssd attached and read/write performances increased a lot with passthrough; here is the relevant topic:

 

not the same case, but usually passthrough is the best option you can have without nearly any overhead due to emulated controllers/disks.

Note that my ssd was the array (I know, it's wrong) and note the cache.

On the contrary, without any doubts, having a vdisk it's a matter of seconds to do a backup...just shutdown the vm and copy somewhere the vdisk image.

So...your choice!

Edited July 19, 2021 by ghost82

[mkaszas]

Thanks @ghost82! I really appreciate your detailed answer.

2nd option seems great, but also I might create another osx vm and use a virtual disk there and add an nvme as cache. Maybe the performance would not be as good as now but backup/restore would be really easy. Will test it.  

 

[ghost82]

1 minute ago, mkaszas said:

but also I might create another osx vm and use a virtual disk there and add an nvme as cache.

Yes, I agree, directly testing it's the best option, maybe with the nvme in cache you could reach good and acceptable performances.

All you need is some time to set up all, but if I were you I would try.