Carl Hutzler’s Blog

I set-up Time Machine successfully to backup to a network attach storage device (ReadyNAS 1100) twice now and have had great reliability. But for some reason, I have been trying to do it a third time at a client site and it will not work. I have been getting errors like:

Backup failed with error: 19
Network mountpoint not owned by backupd… remounting

I looked all over the ReadyNas.com site and followed their instructions perfectly. And I searched all over the blogs and other folks are having the same issue. Some think it is permission problems and I have no doubt some people have a lack of write access to their network share. But this was not the case for me.

What I found worked was after choosing the Time Machine volume in Time Machine preferences, you have to EJECT the time machine afp share (and sparse disk image if you had it mounted) BEFORE time machine will be happy and start backing up. I think it is because initially you had the share mounted as “you”, a normal user. And when time machine runs it wants to mount the share AS THE OWNER (backupd) in some way. If the share is already mounted as “you the user”, time machine can’t mount it as itself.

So when you choose the time machine volume for backups and the time machine preference says “backup starting in 120 seconds…119 seconds…118 seconds”, just eject the time machine AFP share and it just might work for you.