Internal or external SSD for TrueNAS SCALE boot pool?

[pinoli]

I gather that the consensus today, and the official recommendation, is to use SSDs as boot devices.
I was wondering though, if this means *internal* SSDs only, or if it refers to *external* SSDs as well.
I would also know if you would rather install the OS on internal NVMe or SATA SSDs.

Since I would like to maximize my internal SATA ports for storage, I would like to know if this product could be an optimal solution for my TrueNAS SCALE rig.
It's an external SSD from SanDisk (now part of Western Digital), part number is SDCZ880-128G-G46, link here.
My idea is to get two of these, and put them in a mirrored boot pool.
Or, if NVMe are better, I'd buy two NVMe USB3 enclosures instead of the SanDisk USB sticks.

At the same time, I would like to know if installing the OS on *internal* SSDs is better for performance, stability or any other reason.
I can definitely make room for two drives, whether they are NVMe or SATA SSDs, so storage expansion is not a problem here.
But for obvious reasons, I would love to use the external USB ports, that would go otherwise unused.

Thanks, happy to hear your suggestions/recommendations.

 

[pinoli]

I am not sure this subforum is the right place, but I am interested specifically about TrueNAS SCALE. I read the docs that recommend SSDs, but there is no mention whether they can also be external.
I think it's a pretty straightforward question, can anyone help me out?

 

[danb35]

Short answer: there's no intrinsic reason you can't use an external SSD; the SSD itself will behave the same whether external or internal. The potential issue is the USB interface. For data pool disks, we generally find that USB doesn't work very well, but I don't think there's much of a base of experience with USB SSDs for boot.

 

[pinoli]

Thanks for your reply.
My question stems exactly from the fact that there is not much on the internet about it.
I am aware the problem can be the USB controller, and that's the reason I wanted to know if someone else tried it with 2 external USB SSDs as boot pool.

I know TrueNAS SCALE is still in alpha, so I am sure there won't be many that tried this configuration, but I would love to hear from them.

 

[sretalla]

I don't think there's much of a base of experience with USB SSDs for boot

I have seen plenty of others reporting good success with USB to SATA adapters and SSD as boot... I think @Yorick has been one who has confirmed it in the past (as an example I can easily recall... https://www.truenas.com/community/threads/mirrored-boot-drive-usb-2-0-or-3-0.86963/post-602824).