fatvegan

It seems that some versions of Mac OSX have some broken sparsebundle handling over AFP (Apple Filing Protocol). Time Machine uses sparsebundle's for backups. The consequence is that using Time Machine with a network-connected external hard disk (like the Netgear Stora) fails. I've spent a lot of time on various forums, reading Apple support articles and reading Netgear support articles. None of the suggestions helped, with the eventual exception of some vague advice to create the sparsebundle file manually. That advice, in fact, worked.

I did something a little like this.

1. Open Applications > Utilities > Disk Utility.
2. On your local hard drive, create a new disk image with a large Volume Size (200GB in my case), Volume Format 'Mac OS Exended (Journaled)', Partitions 'Apple Partition Map', Image Format 'sparse bundle disk image'
3. Find out the name of the sparsebundle the Time Machine wants using the Time Machine Buddy widget. Start a backup and watch the log when it fails.
4. Move the sparsebundle on your local hard drive to your network drive. If Time Machine is saying it can't create '/Volumes/sharepoint/MachineName_0023ef94d1fc.sparsebundle' then move the file there.
5. Try starting the Time Machine backup again. You may need to mount the sparsebundle image first.

My log before this process...

Starting standard backup
Mounted network destination using URL: afp://user@192.168.1.102/share
Backup destination mounted at path: /Volumes/share
Creating disk image /Volumes/share/MachineName_0023df97d1fc.sparsebundle
Error 45 creating backup disk image
Failed to create disk image 
Backup failed with error: 20
Ejected Time Machine network volume.

My log after it...

Mounted network destination using URL: afp://user@Stora._afpovertcp._tcp.local/share
Backup destination mounted at path: /Volumes/share
Disk image /Volumes/share/MachineName_0023df97d1fc.sparsebundle mounted at: /Volumes/200GB

Backing up to: /Volumes/200GB/Backups.backupdb
Event store UUIDs don't match for volume: Macintosh HD
Backup content size: 81.5 GB excluded items size: 9.7 MB for volume Macintosh HD
No pre-backup thinning needed: 97.80 GB requested (including padding), 197.78 GB available

Can't account for difference between IP URL in failed backup and Stora.afpovertcp.local URL in successful backup.