SSD vs SATA DOM vs M.2 vs USB - "Best" boot drive option ?

[EPU]

I've been browsing the forum and can't seem to find a definitive answer to the thread title. The last real discussion on this seems to be from 2016 (where there are a number of threads discussing the use of M.2 drives), but nothing really since then. A couple of threads from 2014/5 said that iXsystems were favouring SATA DOM at that time, but what's the consensus now ?

From what I can gather, the main arguments for/against each are as follows

SSD - Considered to be the most reliable, but potentially the most costly, and takes up a SATA port (or 2 if you mirror).
SATA DOM - Cheaper than SSD, but again takes up a port (or two), and can be difficult to get hold of for a reasonable price.
M.2 - Keeps SATA ports free, but difficult to mirror (not many server class boards have 2 x M.2 slots). Often cheaper than both of the above, and fairly reliable.
USB - Cheap, easy to mirror, and keeps all slots free. Highest probability of failure compared to the others, hence encouraging mirroring the devices.

I'm in the position where all of the above are options for me, so am completely open to suggestions as to which would work the best. I don't really want to have to worry about reliability, so is the dual SSD route the best option or something else ?

 

[Johnny Fartpants]

I always use a mirrored pair and personally use SSD. I've had/have some units with SATA DOMs and although they are fine when one breaks (which they do from time to time) it's a bit of pain to access it as it requires pulling the server out of the rack (in my case) and opening up the lid. I've used many USB boot sticks over the years and again they are fine but nowhere near as good as SSD. I've never used M.2 for this.

I would say for a cheap/test system then USB in a mirror is fine. For a system whereby you don't have space for an extra 2 drives then SATA DOMS are a good option. But if you are able to use SSD's then do so. Go for something small and reliable like Intel and 40GB should be plenty.

 

[blanchet]

In my system, I use a small SATA SSD with a USB-to-SATA3 adapter.
I stick the SSD in the chassis and I use the internal USB port of the motherboard.

It provides a reliable solution (with SSD) that avoids taking a SATA port.

 

[Chris Moore]

It's not worth the cost of putting a M.2 drive in the system as a boot drive. Wasted money.

 

[inis]

It's not worth the cost of putting a M.2 drive in the system as a boot drive. Wasted money.

um you can get them pretty cheap now, my boot drive is m.2 does 2200 read and 1400 write, was 24 bucks at microcenter.

 

[Chris Moore]

um you can get them pretty cheap now, my boot drive is m.2 does 2200 read and 1400 write, was 24 bucks at microcenter.

My boot drive was $5 and there is no need for speed in a FreeNAS boot drive. A mechanical drive is faster than fast enough.

 

[HoneyBadger]

A mechanical drive is faster than fast enough.

And 640KB should be enough for everyone, right? ;)

While there's no reason to spend more than you have to, if you have a motherboard that has already devoted a SATA port to an M.2 slot (or if it has an NVMe one and you don't foresee an SLOG in your future) and you want to keep all of the other ports free for data drives (or are building in a space-constrained chassis) then the extra $15 might be easily justified to that particular user.

 

[gsrcrxsi]

I posted this in another thread but maybe it's more appropriate here.

If I want to run a Mirrored SSD boot drive, Is there any reason one should mirror the OS boot drive from within FreeNAS vs just using the motherboard onboard RAID controller to create a RAID1 mirror and install the OS to that?

 

[anmnz]

Put it the other way round. If you're already going to be running FreeNAS, is there any reason one should mirror the OS boot drive using some other proprietary closed-source undocumented RAID software running in a tiny, extremely resource-constrained environment vs just using FreeNAS to create a mirror?
:)

 

[gsrcrxsi]

That doesn’t answer the question.

I’ve built MANY raid1 arrays via the built in Intel controllers on Supermicro boards. They are very reliable. But I’ve never done it for FreeNAS boot. I just wanted to check that there isn’t anything inherently different with the way FreeNAS boots that would cause an issue. It sounds like there’s no reason not to since you couldn’t provide any. The upside I can see is that it doesn’t depend on FreeNAS to manage the mirror. And in the event of a drive failure It will still boot properly.

One of my systems runs on a single 40GB SSD, and I want to make that a mirror. Another system runs on a 16GB flash drive that I want to also migrate to a 40GB SSD mirror.

It seems the only downside is that I will need to resinstall FreeNAS to my new RAID1 array and reimport the config file.

Anything else?

 

[anmnz]

FreeNAS won't have access to the underlying drives so can't report on problems. FreeNAS won't be able to run regular SMART tests or scrubs. FreeNAS won't be able to detect and correct data corruption. FreeNAS won't be able to report on the state and health of the individual drives in its UI along with all the other reporting in the system. And so on. Lots of reasons. Same obvious reasons you'd use FreeNAS in the first place. I'd have thought they would carry at least some weight if you're already using FreeNAS.

But it sounds like what you actually want to know about is total showstoppers that would mean you couldn't run FreeNAS from your motherboard's RAID no matter what, and I'm quite sure there aren't any of those.

 

[gsrcrxsi]

Thanks for the info.

Is it possible to mirror an existing boot drive without destroying it? Like just copying it over to a drive I add to the system without doing a full OS reinstall

 

[gpsguy]

I don't see it in the new GUI, but in the Legacy GUI, one can mirror the boot pool by using the "attach disk" button. See - https://www.ixsystems.com/documentation/freenas/11.2-U5-legacy/system.html#mirroring-the-os-device

Is it possible to mirror an existing boot drive without destroying it?

 

[Chris Moore]

Thanks for the info.

Is it possible to mirror an existing boot drive without destroying it? Like just copying it over to a drive I add to the system without doing a full OS reinstall

There is a method in the GUI for adding a mirror to an existing single disk boot pool. It is documented in the manual.

This video might help:
https://www.youtube.com/watch?v=1AxDtHEA-rM