I was having some trouble with a large Open Directory installation recently – users were able to authenticate, but never saw their desktop – they got a "you are unable to log in at this time…" error instead, then were logged back out.
After some googling, I found a story on macosxhints.com’s discussion boards about bad aliases in /Volumes. I checked /Volumes on my server, and sure enough, though the Homes mount record pointed to /Volumes/ServerRAID, the homes were actually at /Volumes/ServerRAID 1 (note the 1!).
What had happened was simple but had pretty bad side effects – I had found that the admin previous to me had set two of the Xserve’s drive modules to fucntion as a striped RAID (!) – very bad for user data – I had cloned the drive (with bombich.com CCC) to an external firewire disk, then changed the RAID to a mirrored one, cloned from the firewire to the RAID, then removed the firewire disk.
The problem with this was that CCC also clones the volume name – you see on your desktop two disks with the same name, but Darwin needs to differentiate between disks – hence adding the "1". Unplugging a firewire disk unmounted it, but didn’t remove the alias (ServerRAID) to it in /Volumes. The new RAID continued to be called "ServerRAID 1" – and that, of course, confused clients looking to automount a home in /Volumes/ServerRAID – which no longer existed.
It’s not easy (possible?) to rename an alias, so I waited till the server could be shut down, booted down, removed the RAID drive modules, booted in single user mode (fsck’ed the disk to be safe) – checked /Volumes and deleted any stray alias files, shut down again (shutdown -h now), reinserted the RAID modules, booted, and all was immediately well with user logins.
So, keep an eye on /Volumes if you have Home Dir troubles. (Anyone know a way to make the Finder display all the unix stuff?)
(ed. note. "defaults write com.apple.finder AppleShowAllFiles ON" will show all files in the Finder and you can always use the "Go To Folder…" command to navigate to hidden folders. You might also want to check /private/var/automount/Network/Servers –pre 10.3.5– or /private/Network –10.3.5 on– on the client side for network home folder issues.)