Vinum question

[pkddeckard at ziplip.com]

I'm considering migrating a Linux server over to 4.8-RELEASE.  The Linux server has a bootable software RAID set up, where there are three disks configured for a RAID-1 volume, two of which are currently active and one of which serves as a standby disk (to allow for two disk failures in close proximity).

I've looked through both of the manpages for vinum and Chapter 13 of the Handbook, but I can't seem to locate any kind of similar feature.  Am I missing something, or will I have to write my own program to handle configuring standby disks in case of a failure?