vxdisk offline failing with device in use error

[Jani Tamminen]

Our Sun Fire 480 crashed and I rebooted it with the mirror root disk.

following is the output of vxdisk list:

DEVICE TYPE DISK GROUP STATUS
Disk_1 auto:sliced rootdg01 rootdg online failing
Disk_2 auto:sliced rootdg02 rootdg online
Disk_8 auto:none - - online invalid
Disk_9 auto:none - - online invalid
Disk_10 auto:none - - online invalid
Disk_11 auto:none - - online invalid
Disk_12 auto:none - - online invalid
Disk_13 auto:none - - online invalid

I rebooted the server with the mirror rootdg02. Now I am trying to replace
the Disk_1.
I tried vxdisk offline Disk_1, it complains that *device in use.*
How do I offline that that Disk_1? Do I need to use the other name c1t1d1S2
to offline the disk?

-JT