Failure to power off a Tempo card before ejecting it may have an unpredictable result for OS X.
You should follow these steps:
1. Unmount any drives attached to the Tempo card by dragging them to the Eject icon in the dock.
2. Click the Card's icon in the menu bar and select "Power Off Card" from the drop down menu.
3. Push and release the Tempo card to eject.
Using a Drobo S with a Macintosh and Sonnet Tempo SATA E2P, Tempo SATA ExpressCard/34, or Tempo SATA Edge ExpressCard/34. you may get a device removal error after waking up from sleep. The Drobo S will automatically reconnect. System caches are flushed before sleep, so there is not data loss.