Installing boot on USB but using new dataset in existing pool for root and the rest

[gsa-toolbox]

I'm currently running TrueNAS core with a "hybrid pool" leveraging 2 small SSDs in mirror for metadata/small files and 4 HDDs in RAID Z2 for capacitive storage, this uses all my available SATA ports.
My boot is using two USB keys in mirror and this does the job very well.

I'd be happy to migrate my system to SCALE and do not fear any problem with my ZFS datasets nor having to migrate a few jails to containers or virtual machines but I have a concern with the boot.
Unfortunately; it looks like SCALE only supports (or strongly recommends) to put the OS on a regular disk which I can't as my ZFS hybrid pool uses all my 6 disks.
It would be great to offer the possibility to do a more custom install with only EFI and boot on USB, and to use an existing pool with new dedicated datasets for the root FS etc.
I'm pretty sure this can be hacked rather easily by installing on USB and then moving all but EFI/boot to the main dataset but a native support would be a lot more reliable.
Anyone has any thoughts about this?
Cheers,

Guillaume

 

[sretalla]

SCALE only supports (or strongly recommends) to put the OS on a regular disk

So does CORE.

You can do it on USB if you must.

 

[gsa-toolbox]

I suppose that I found an alternate and better option and would like to share: I'll probably go with a managed eUSB DOM (Virtium VTDU41PI016G) attached directly to the motherboard. These aren't cheap but an industrial 16G SLC fully managed (built-in S.M.A.R.T.) should be perfect and I can probably afford skipping on the boot mirror as long as I backup the config regularly. I can also mirror once on a USB key (and after every upgrade) and then unplug the USB key to keep it as an emergency only boot device.
In any case, I'll be playing with TrueNAS scale in a staging environment and wait until it reaches the RELEASE status (and even possibly the support of LXC containers) before I migrate everything.