Not all disks come back after power cycling a JBOD

[Alan Somers]

If I remove a hot-swappable SCSI drive and reinsert it, FreeBSD always
seems to handle that just fine.  But if instead I unplug or power off an
entire JBOD, then reattach it, frequently FreeBSD fails to fails to
recreate all of the device nodes.  Using "mpsutil show devices" or "mprutil
show devices" I can see all of the devices that I'm expecting.  However,
"camcontrol devlist" doesn't show them, and "camcontrol rescan" doesn't
help.

This has been the situation for as long as I can remember, several years at
least.  But now it's starting to cause problems for me.  Before I try to
debug this myself, does anybody know anything about the problem?