Akonadi, Baloo, etc

[Jonathan Ryshpan]

What is akonadi?  What is baloo?  Why does akonadi usually crash on
system startup?  Why does akonadi or maybe baloo sometimes use 100% of
cpu?  Why does akonadi or baloo cause a great deal of disk activity? 
Is there any way to run KDE alarm without akonadi?

Thanks - jon