A friend of mine has his TimeMachine volume on a NAS. That means it's a sparesebundle on the NAS disk.
When he tried to recover, he found that his TimeMachine image was hosed. Looking online, they recommended using hdiutil to attach, then fix the volume with fsck. But... he couldn't attach it when using sudo. After some more searching, he found a page that recommended logging in as root, and then performing the hdiutil/fsck runs. This actually worked.
So: What is the difference between root and sudo in this case?
Are there things that use real Vs effective IDs? are there helper daemons/threads that need to run privileged? Perm squashing over afs (not sure if it does the same as nfs)?