Storage question - Hardware RAID


I have a question about TrueNas requirements and recommendations. TrueNAS is to be installed as a VM on Xen.

TrueNAS Minimum Requirements

  • 64-Bit CPU
  • 8 GB RAM (16 GB Recommended)
  • 16 GB Boot Drive (SSD Encouraged)
  • At Least One Attached Disk
  • Network Port
  • Hardware RAID Not Recommended

The storage pool where the VM disk will be installed is over hardware configured RAID6.
What is the impact of underlying RAID and why is it not recommended? Thank you.

ZFS needs/wants direct access to the disks (even via HBA). Putting “RAID” in between them in a recipe for disaster.

A gem from the old forums:

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Hi @winnielinnie thank you for your reply.

I’m a bit divided on this issue. RAID controller on this server is a Dell PREC H710 Mini. This controller does not have HBA or passthrough mode.
So I understand the merits of the topic provided, was an interesting read despite disagreeing slightly regarding the maturity of some drivers, but currently attaching disks directly is not an available option.

We do have some VM’s with underlying ZFS storage on this pool, and also on other pools in different setups and so far I can’t say we’ve ever experienced any issues.
But will consider a different setup for the future with dedicated hardware.

@maverick The general challenge is “what is the TrueNAS installation being used for?” For non-production or testing purposes, a virtual disk is fine, but when using this for production storage, we recommend PCI passthrough of a supported storage controller. See the blog below for some details.


@HoneyBadger thank you for your reply.

Right now I’m planning to use this TrueNAS for:
File storage, cold archives
Time Machine Backups

I don’t know if TrueNAS allows setting up a DLNA server if so that would be a plus, but won’t be an heavy usage of NAS like if I was using it for VM disks.