SATA DOM Boot Device RAID

[Pistolwhip]

Hi all; long time lurker, first time poster.

I'm currently building a new storage system and I'd like to make use of my motherboard's onboard SATA DOM ports (there are two).

They're on an Intel controller which supports basic RAID functionality. Since I'm using exclusively HBAs for serving my data drives, I was wondering if it was possible to configure the DOMs in a RAID-1 and run FreeNAS from there.

Some searching hasn't net many results either on the forums or in the official documentation, and in my trial and error investigation I wasn't able to make it work.

I guess I'm looking for some guidance as to how to accomplish this, or in lieu what the best practice is to take advantage of the two ports to best protect my install.

When attempting on my own, in the Installer the DOMs seem to be listed twice. First it sees both DOMs independently, and then at the very bottom it lists an 'unknown' raid device with the expected size.

Attempting a test install to the RAID device fails.

As does resetting everything and attempting to install on the DOMs directly.

High level system specs are are:

X10SRL-F
Xeon E5-1650v3
64GB Registered ECC
9211-8i HBAs (IT Mode M1015's)
Supermicro DOM modules (a pair)

Any insights and assistance would be greatly appreciated. Note I'm not married to the idea of RAID for the DOMs, I'm just looking to best utilize the redundancy they afford.

 

[gpsguy]

Don't try to use hardware RAID to mirror them. When you do your FreeNAS install, select both DOM's for the target device(s).


Sent from my phone

 

[Pistolwhip]

Thanks for the reply. The install went fine after deleting the RAID, and switching the onboard controller back to AHCI.

Just for my clarification, what exactly does selecting both during installation do? Is FreeNAS managing a mirror or something similar? Just want to understand exactly how this changes an install.

 

[gpsguy]

If you look at the "Compact or USB Flash" (it still applies to SATA) portion of the manual - http://doc.freenas.org/9.3/freenas_intro.html#compact-or-usb-flash the last line in that section reads "if a reliable boot disk is required, use two identical devices and select them both during the installation. Doing so will create a mirrored boot device"

FreeNAS 9.3 allows one to mirror the boot device. One can either do it on a fresh install (like you did) or after the fact, http://doc.freenas.org/9.3/freenas_system.html#mirroring-the-boot-device

I *think* some users have run into problems with the second method (2nd disk slightly smaller?), whereas using the first method and doing it at install, adjusted for the slight differences. In your case, it doesn't matter.