gmirror Cannot access provider da0

[jd]

I'm trying to set up gmirror for the first time using instructions in
the Handbook. I get this error:

grenvil# gmirror insert gm0 /dev/da0
Cannot access provider da0.

>From dmesg:

da0 at ahc0 bus 0 target 0 lun 0
da0: <IBM DNES-309170Y SA60> Fixed Direct Access SCSI-3 device
da0: 80.000MB/s transfers (40.000MHz, offset 31, 16bit), Tagged Queueing
Enabled
da0: 8683MB (17783301 512 byte sectors: 255H 63S/T 1106C)
da1 at ahc0 bus 0 target 1 lun 0
da1: <IBM DNES-309170Y SA60> Fixed Direct Access SCSI-3 device
da1: 80.000MB/s transfers (40.000MHz, offset 31, 16bit), Tagged Queueing
Enabled
da1: 8683MB (17783301 512 byte sectors: 255H 63S/T 1106C)
GEOM_MIRROR: Device gm0 created (id=2172298823).
GEOM_MIRROR: Device gm0: provider da1 detected.
GEOM_MIRROR: Device gm0: provider da1 activated.
GEOM_MIRROR: Device gm0: provider mirror/gm0 launched.

How can I fix this problem?

Janos Dohanics