Re: Over a barrel. @AC
Having just read a Technet description of Kerberos constrained delegation, it would appear that Microsoft have implemented a service using a fundamental feature of Kerberos - which appeared on a number of platforms including UNIX before it was added to Windows, and have been presumptuous enough to have given it a name.
Linux implementations of Kerberos will have the same fundamental technologies, but nobody has given it s specific name except Microsoft, who are trying to cash in on other people's work. I'm pretty certain that all Linux distro's will have Kerberos 5 support in their repositories. RHEL6.5 certainly has.
There are also several deduplication facilities available for Linux, including a number of filesystems like btrfs and ZFS. You just have to use a search engine to find them. ZFS also supports tiered storage (before Windows 2012, btw), as does IBM Elastic Storage, although Elastic Storage (aka GPFS) is commercial software.
I admit that it's not out-of-the-box, but it's hardly difficult to come by.