[PVE-User] Limited number of virtio-devices/drives

Keri Alleyne k.alleyne at symlogix.com
Mon Aug 3 18:21:08 CEST 2015

On 08/03/2015 03:02 AM, Emmanuel Kasper wrote:
>> We currently have a customer evaluating a system with 16 x 12Gb/s SAS
>> drives driven by an HBA. They have intentions of building systems with
>> 24 bays and 24 SAS drives.
>> Maybe we are going about this all wrong and perhaps there is a smarter
>> way to do this....however....
>> The customer's software is based on FreeBSD/NAS4Free. This runs on
>> Proxmox VE as a VM.
>> The VM's conf file looks like this snippet:
>> virtio0: /dev/sda
>> virtio1: /dev/sdb
>> virtio2: /dev/sdc
>> virtio3: /dev/sdd
>> virtio4: /dev/sde
>> virtio5: /dev/sdf
>> virtio6: /dev/sdg
>> virtio7: /dev/sdh
>> This is to allow the software to see the drives in the GUI and also to
>> provide max performance....we think. We are also considering PCI
>> passthrough options to have the VM see the HBA card directly.
>> The FreeBSD system will then use these drives to create a zpool.
>> With a limit of 16 Virtio disks, it seems that we can't use this
>> approach to operate 24 disks.
>> Any suggestions? Any creative approaches to work around this problem?
> Hi Keri
> The FreeNAS folks have a good post on how to virtualized FreeNAS, most
> of it will apply to Nas4free and KVM.
> https://forums.freenas.org/index.php?threads/please-do-not-run-freenas-in-production-as-a-virtual-machine.12484/
> Don't be scare by the title, it does work, but you have to pay great
> attention to what you are doing ( I am myself having such a setup)
> As Michael and the FreeNAS folks says you absolutely  have to PCI pass
> through your storage controller, as ZFS expects to have access to the
> real device.

Thanks much Emmanuel.
The page has been bookmarked - going to take a closer look once I can 
liberate some time on this end.

I've seen this some months ago: https://pve.proxmox.com/wiki/Pci_passthrough

The article links to: 

But as your link seems to be more current - I'm hoping for better 
results or at least good advice to get me started.

Thanks again for the great help.


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