I run Time Machine with multiple backup disks - one always mounted, and a few more (on an Airport Extreme) rotated where at least one is always off-site. With Mountain Lion, I would get a daily alert that "backup foo hasn't been successfully backed up in 'n' days". With two offsite backups, I would get two such alerts per day - one for each. Annoying, but not too bad. With Mavericks, each and every single attempt (i.e., every hour or two) to back up to one of these off-site drives results in an alert in the Notification Center. And it doesn't even note which set failed or when (without going to the TM preferences, and then it only gives you the last successful date, not the Backup Disk name). And... it usually ends up that my Time Machine menu icon is usually the "alert" one. This is really annoying, and (in my case) makes the notification feature pretty useless regarding real failures. I can't modify the Time Machine notification settings at all (on either the Time Machine or Notifications side). They just don't appear anywhere. I can't temporarily disable a Backup Disk. There is no feature to do that. I don't think that I'm willing to remove an offsite Backup Disk from Time Machine's list. It may compromise data restores, and at the minimum I think it'll cause massive disruption when the rotating backup returns and is reconnected. So how do we complain to Apple about this "over-reach"? Or am I all wet trying to do off-site backups with Time Machine?