Unexpected error using mdimport

If you are using mdimport and get the message Can't checkin with server named com.apple.metadata.mdserver, then it’s quite possible that Spotlight’s metadata datatore is broken. To fix the problem run sudo mdutil -E /Volumes/MyVolume to erase the broken datastore.
If the error occurred on a Xsan volume, it may be a good idea to unmount the volume on all client computers but one (the one where you will run the mdutil command from).