Mirroring boot drive with 9.3 - worked fine for me

[Arwen]

When I bought my FreeNAS Mini, it did not come with mirrored boot drives. That was always something I wanted
to do, simply to reduce future headaches.

Looking at the Mini's boot device, it is a 16GB SATA DOM, (Disk On a Module). The Mini has plenty of extra
SATA ports, so I thought I would do the same thing, SATA DOM instead of USB. Next, because of discussons
indicating that USB & DOMs don't have standard sizes, I went up one size, to 32GBs.

Reading comments about some SATA DOMs, it was a mixed bag. SuperMicro's seemed good so I went with their
32GB, (and additional power converter cable since I am not using a SuperMicro motherboard). Installation was
easy, and the FreeNAS 9.3 manual was pretty clear.

If the size of the 32GB DOM from SuperMicro is twice as large as their 16GB DOM, then it was a good thing I
went with the larger size. My existing 16GB DOM is larger than half the SuperMicro 32GB DOM.

My take away from this experience, is that I would like to see a FreeNAS advanced installation option to reduce the
boot pool by 512MBs or 1GB. That's so that we can have a better chance of adding a mirrored boot device later,
using the same rough size. In my case, it would have been just a few hundred mega-bytes difference.


Anyone else using mirrored boot drives?

Did / do you have any problems?

 

[Ericloewe]

You make a good point that has bitten people in the ass previously, but I don't think it's on any roadmap.

This is only a problem when adding/swapping mirrors. If done during installation, everything goes smoothly, regardless of small differences.

It seems there's a new installer on the way for FreeNAS 9.3 already, so let's see how it behaves before filing a bug report.

 

[Arwen]

If there is not already a bug report / feature request for that issue, then I won't create one.
But, if / when one is created, I'll add my 2 cents worth to the bug report / feature request.

 

[mjt5282]

I use 2 USB drives, one primary and one mirror for my backup NAS. The throughput for the USB 2.0 drives is not great but the mirroring reports as working. USB drives do tend just to die off (I use a UBNT linux firewall that has cheap flash storage and tends to die after the warranty expires). My primary NAS uses a 16Gb DOM so I was thinking about buying some more DOM packages from newegg. Having a mirrored root seems like a good policy, when all the other data is raidz2 mirrored.

 

[Arwen]

mjt5282,

Remember, if you can't get the exact same brand and size, you have 2 choices;

1. Buy one size larger
2. If new DOM is smaller, re-load to this smaller DOM, then mirror to larger DOM.

I lucked out in that my SuperMicro 32GB SATA DOM was also much faster, (450MBps
reads, about half that for writes), than my existing 16GB SATA DOM.