ThinkPad X3 UltraBase
The UltraBay Plus slot in this dock is a full featured one and supports hot swapping with all UltraBay Plus and UltraBay 2000 drives. You can also feed it with the UltraBay Plus battery pack to extend the overall battery life time.
This can be problematic under Debian, as the default kernels do not support the IBM docks. I had to recompile it to enable CONFIG_ACPI_IBM_DOCK, and disable CONFIG_ACPI_DOCK. I also needed to hook a few scripts into the acpi events system.
#!/bin/sh # acknowledge docking with the dockstation echo dock > /proc/acpi/ibm/dock
#!/bin/sh # prepare the laptop for undocking with the dockstation echo undock > /proc/acpi/ibm/dock
event=ibm/dock GDCK 00000000 00000003 action=/etc/acpi/ibm-dock.sh
event=ibm/dock GDCK 00000003 00000001 action=/etc/acpi/ibm-undock.sh