Mirroring 2 hard disks by soft for high availability

[Dario Goldfarb]

Hi,
    Im trying to mirror two disks to accomplish high availability on FreeBSD
4.8-RELEASE.
    I've configured Vinum with the following configuration :

    drive d1 device /dev/ad0s1e
    drive d1 device /dev/ad2s1f
    volume mirror setupstate
        plex org concat
            sd length 32g drive d1
        plex org concat
            sd length 32g drive d2

    This is working fine I have a 32 gb partition mounted on /data
    I think this should be writing the data on both partitions, right ?

    The problem is that when i take off the secondary disk to ensure that on
a disk failing it will keep on working, it dies with a kernel panic after
booting (right after the login screen). can anyone tell me what im doing
wrong ?

Thanks a lot in advance
Dario Goldfarb.