diff --git a/share/man/man4/sbp.4 b/share/man/man4/sbp.4
index 72d9241cdbe1..2b2e6f5206d9 100644
--- a/share/man/man4/sbp.4
+++ b/share/man/man4/sbp.4
@@ -58,6 +58,15 @@ driver provides support for SBP-2 devices that attach to the firewire
 It should work with SBP-2 devices which CAM layer supports, for example,
 HDD, CDROM drive and DVD drive.
 .Pp
+Some users familier with
+.Xr umass 4
+might wander why the device is not detached at the CAM layer when the device
+is unplugged. It's detached only if the device has not been plugged again
+during several bus resets. This is for preventing to detach an active filesystem
+even when the device cannot be probe correctly for some reason after a bus reset
+or when the device is temporary disconnected because the user changes the bus
+topology. If you want to force to detach the device, run 'fwcontrol -r'
+several times.
 .Sh SEE ALSO
 .Xr camcontrol 8 ,
 .Xr firewire 4 ,