FreeBSD 10.1 i386 encrypted mirrored ZFS root on USB flash drives

[David Christensen]

freebsd-questions:

I have a computer with an Intel D945GNT motherboard, Intel Celeron D 
2.53 GHz processor, and 1.5 GB of memory.  I am trying to install 
FreeBSD 10.1 i386 with encrypted mirrored ZFS root on two USB flash 
drives, rather than hard disk/ solid state drives.


I have installed FreeBSD via FreeBSD-10.1-RELEASE-i386-memstick.img as 
follows:

     "Welcome to FreeBSD" -- choose "1. Boot Multi User".

     "Welcome" -- choose "Install".

     "Keymap Selection" -- choose ">>> Continue with default keymap".

     "Set Hostname" -- enter "cd2533".

     "Distribution Select" -- accept default selections:

	games
	ports

     "Partitioning" -- select "Auto (ZFS)":

	"Pool Type/Disks" -- mirror: 2 disks:

	    mirror

	    da1  SanDisk Ultra Fit
	    da2  SanDisk Ultra Fit


	"Pool Name" -- "cd2533".

	"Force 4K Sectors" -- "YES".

	"Encrypt Disks" -- "YES".

	"Partition Scheme" -- "GPT".

	"Swap Size" -- "1g".

	"Mirror Swap" -- "YES".

	"Encrypt Swap" -- "YES".

	Choose ">>> Install".

	"Last Chance" -- choose "YES".

	Enter and confirm passphrase.

	Enter and confirm root password.

	"Network Configuration":

	    Select "em0"

	    "IPv4" -- "YES".

	    "DHCP" -- "YES".

	    "IPv6" -- "NO".

	    "Resolver Configuration"

		"Search"	-- holgerdamske.com
		"IPv4 DNS 1"	-- 192.168.1.1
		"IPv4 DNS 2"	--


	"Set Local or UTC Clock" -- "NO".

	"Time Zone Selector" -- "America North and South" -- "United
	"States" -- "Pacific Time".  Confirm "PST".

	"System Configuration" -- select:

	    sshd
	    ntpd
	    powerd
	    dumpdev

	"Add User Accounts" -- "NO".
	
	"Final Configuration" -- "Exit".

	"Manual Configuration" -- "NO".

	"Complete" -- "Reboot".


When I power up the machine, it does not boot from the flash drives, 
even if I manually select either of the flash drives via F10 POST boot menu.


I have configured my BIOS CMOS settings to boot from the flash drives 
and to boot from USB devices first.


Is it possible to install and run FreeBSD from flash drives?


Any suggestions?


David