I successfully built up a raid5 array on Debian testing (Wheezy). As the man pages and further tell, the array would be created as an out-of-sync array with just a new spare injected to be repaired. That worked fine. But after the rebuild process, I get daily messages on missing spares, but the array should be raid5 over 3 discs without spares. I think I only need to tell mdadm that there is -- and should be -- no spare, but how to?
mdadm -D gives
Active Devices: 3 Working Devices: 3 Failed Devices: 0 Spare Devices: 0
md1: active raid5 sda3 sdc3 sdb3 ##### blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]