I think Allan has implemented booting ZFS from a GELI encrypted drive:
https://www.bsdcan.org/2016/schedule/attachments/382_BSDCan2016_GELIBoot.pdf
and again
http://www.allanjude.com/bsd/AsiaBSDCon2016_geliboot.pdf
new and improved - with unattended booting
https://archive.fosdem.org/2018/schedule/event/zfs_advanced_integration/
and a howto
https://ftfl.ca/blog/2016-09-17-zfs-fde-one-pool-conversion.html

this is complicated enough that I would want to get the books before I took
on anything this ambitious - please keep us up on how you deploy

On Sun, Sep 23, 2018 at 11:35 AM Matthew Crews <mailinglists@mattcrews.com>
wrote:

> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> On Sunday, September 23, 2018 12:20 AM, Stephen Partington <
> cryptworks@gmail.com> wrote:
>
> > My experience with zfs has been for large file servers. Never in a
> workstation environment. Really nice once you got used to its nuances. As
> it was for filer use I did not care about the ram used.
>
> As far as RAM usage, ZFS is relatively RAM intense. I would budget about
> 1GB ram per 1TB of storage, 1GB per 50GB of L2ARC (if using L2ARC), and 5GB
> per 1TB of storage if you are using deduplication (dedupe is probably not
> needed except in specific workloads). For fileservers you definitely WANT
> ECC ram, but its not strictly required.
>
> -Matt
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