Apple has confirmed it will offer limited support for Sun Microsystem's ZFS (Zettabyte File System) file system in Mac OS X 10.5 Leopard, which ships later this month.

Speaking to Computerworld, Apple spokesman Anuj Nayar said: "Apple will provide limited ZFS support in Leopard. It will only be available as a read-only option from the command line."

ZFS is an advanced file-system that can store 18 billion billion times more data than 64-bit systems, and has been touted by Mac watchers as a way in which Apple could make Leopard's new Time Machine feature less demanding on hard-drive space.

The file system was first linked to Apple in early June, when Sun CEO Jonathan Schwartz said ZFS would be included with Leopard.

However, Sun's file-system has attracted legal action. Network Appliances filed a patent-infringement lawsuit against Sun last month in a Texas court. The lawsuit accuses Sun of infringing on seven Network Appliances patents within ZFS. It seeks an injunction to stop continued patent infringement, including a halt in distribution of ZFS by Sun or any third party.

If Network Applications succeeds, Apple could be left exposed should it decide to invest heavily in ZFS support within Mac OS X.

Sun donated the ZFS code to the OpenSolaris.org open-source community in April, so the case could emerge as a major test for open-source software, according to Computerworld.