Assigning hard disks directly from the pool vs syncing back to zfs/block host

BitShift

4/8/23, 6:58 AM

What are the specific pros and cons, perhaps even conventions, of attaching a volume to a VM directly from a proxmox zfs pool VS mounting the volume through a file/block storage solution like TrueNAS (which is running inside a VM)?

I have a proxmox server with several VMs, one of them running TrueNAS and another running Linux with all my docker instances (others running various services)

The idea of running absolutely all file/block management for docker-centric VMs (and other files related to other VMs) through TrueNAS is appealing to me but I'm not entirely sure if this is just viewing everything as a nail with TrueNAS as the hammer. It's running on the same hardware, so really less of a concern than perhaps when running TrueNAS on dedicated hardware or even within a proxmox datacenter spread across several nodes.

The alternative is simply creating another hard disk from a zfs pool and attaching directly to a VM. Is this considered uncouth given the option to use TrueNAS?

I feel like migration would become less clean by attaching it directly and not taking advantage of TrueNAS, as from what I have learnt so far in this journey into server: as much persistent storage as can be possibly detached from the core running VM, should be.

EDIT: in the case of docker instances, this would not be storage for dependancy of service, rather storing things like user content and other non-ephemeral data.

0 + 0

zfs

storage

proxmox

truenas

Tero Kilkanen

4/8/23, 4:31 PM

It depends on your requirements. Adding TrueNAS as a layer between ZFS and the actual VM adds overhead to filesystem accesses, so it has some effect on performance. You need to measure the performance effect with your workload, if the overhead is acceptable.

BitShift

4/8/23, 8:36 PM

@TeroKilkanen yeh that's the only thing I can think of as well. There will be some overhead but it feels much neater to handle blocks through TrueNAS, from a mobility pov but then again once I start doing multiple nodes I should really be moving to ceph. The only advantage I can see is from a management pov with docker VMs etc...

Elon Musk

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EN: Assigning hard disks directly from the pool vs syncing back to zfs/block host

TH: Assigning hard disks directly from the pool vs syncing back to zfs/block host

RO: Assigning hard disks directly from the pool vs syncing back to zfs/block host

RU: Assigning hard disks directly from the pool vs syncing back to zfs/block host

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