My Time Machine backs up to a hard drive connected to my Airport Extreme. After I've upgraded to Lion I have noticed that the
mds process (the Spotlight indexer) has been running at 100% cpu every now and then. A simple file activity check told me that it was trying to index my Time Machine backup.
I have gone and added the Time Machine disk to the Privacy list in Spotlight settings, which is supposed to exclude the disk from the Spotlight index, but alas, Spotlight still tries to index it sometimes. Is it a bug in Lion or am I missing something?