Converting to a ZFS rootfs

My main desktop/server machine (running Debian sid) at home has been running XFS on mdadm raid-1 on a pair of SSDs for the last few years. A few days ago, one of the SSDs died. I’ve been planning to switch to ZFS as the root filesystem for a while now, so instead of just replacing the failed drive, I took the opportunity to convert it. NOTE: at this point in time, ZFS On Linux does NOT support TRIM for either …