> IIRC, Solaris could deal with an unrecoverable ECC error by killing the process that had the bad memory. And I think they had hot swap memory on some systems.

Both of these are supported on Linux now. The kill-on-ECC is handled by hwpoison: https://www.kernel.org/doc/html/v5.1/vm/hwpoison.html and the hot-swappable RAM has been present for quite a bit longer.

zfs + solaris zones were amazing