Boot hangs after deleting /var/folders

Number:rdar://20223464 Date Originated:3/19/2015
Status:Resolved Resolved:
Product:OS X Product Version:10.10.2
Classification:Crash/Hang/Data Loss Reproducible:Always
After removing /var/folders (for various troubleshooting reasons documented at from a 10.10 system and rebooting the progress bar proceeds about 50% and hangs - it never boots.  Examining the drive while booted from another source show that the directories are not re-created and the system.log shows many errors about /var/folders/zz does not exist. The same steps taken on a 10.9 system do not result in a hang and upon inspection post-boot show the directories have been recreated.

If only the contents are deleted in 10.10 by running `rm -r /var/folders/*` the system boots fine.
Previous versions of OS X did not exhibit this behavior if the parent directory was removed.

Steps to Reproduce:
1. Boot into 10.10
2. In Terminal run the following `rm -r /var/folders`
3. Reboot

Expected Results:
The computer would reboot and recreate the deleted directories

Actual Results:
The system boots about 50%, the cursor appears on screen but doesn't proceed past that.


Attached the system.log from the 10.10 system.  Filtering for "mkdir" shows many errors of services trying to access a non-existent directory.
The 10.9 log has no entries pertaining to /var/folders after reboot so I didn't find it beneficial to include it in this report.


Apple says this behaves as expected.

"Deleting /var/folders is not supported."

Me: "Dr., it hurts when I press here." Dr.: "Don't press there."

So don't nuke the /var/folders directory.

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