HP File System Technology to Help Drive Linux into Open Storage

HP announced that it is releasing the source code for its Tru64 UNIX Advanced File System (AdvFS) under a license that will allow it to be integrated deeply into the Linux kernel. AdvFS is one of the most proven 64-bit system software technologies in the industry. It offers a number of powerful storage features, including the ability to configure flexible storage pools that can be shared by multiple file systems without needing to add a volume manager; the ability to expand, shrink or reconfigure file systems without taking them offline; flexible transaction log management, including the ability to log both metadata and data asynchronously or synchronously; availability features such as snapshots for consistent backups and support for recovering deleted files; and performance features such as online rebalancing of files and free space across storage pools. Moreover, these advanced features have proven in production for 16 years as a key component of Tru64 UNIX, which itself was one of the most advanced UNIX implementations on the market, before becoming retired in the fallout of HP's acquisition of Compaq.

HP emphasizes that its release of the AdvFS code into open source represents a technology contribution, and is not simply a port that will result in another competing file system for Linux, alongside ReiserFS or Global File System (GFS). The AdvFS code is being released under the same GPL Version 2 license used for the Linux kernel, which means that developers will be able to drive its features as deeply into the kernel as necessary to make them work effectively. HP is actually providing two generations of the AdvFS source code: the existing code taken from Tru64 UNIX, and work-in-progress code that HP produced during its abandoned effort to port AdvFS to its HP-UX operating system. HP is also providing an extensive set of design documentation, test suites and engineering resource related to the code. Linux programmers will be able to refer to this broad base of knowledge as they work on the next-generation Linux file systems currently under development, such as ext4 or BTRFS.

Indeed, it will take several years before the results of HP's AdvFS offering show up in mainstream Linux distributions. Aside from sheer altruism on HP's part, though, the contribution has several implications, both for HP and its customers, as well as the industry at large. First, the availability of proven AdvFS technology on a Linux foundation will make that OS more attractive to any remaining Tru64 UNIX users who may still be resisting HP's recommended migration to HP-UX (even if HP decided to offer innovative migration technology such as Transitive QuickTransit). If these users move to Linux, HP could still retain some as customers, which they could not if the users migrate to a competing UNIX system.

Further, by strengthening Linux storage management functions at the kernel level, HP will help to qualify Linux as a foundation for Open Storage, allowing it to serve as the core software for scalable and reliable network storage solutions that are based on standard hardware. The Open Storage concept has been promoted heavily by Sun with its OpenSolaris initiative, which allows users to couple the advanced storage functions in Solaris, i.e. the ZFS file system, with inexpensive, industry-standard hardware components. As the storage management function in standard operating systems become more powerful, such solutions could start to disrupt traditional enterprise storage systems, most of which are based on proprietary hardware. It is not possible to add ZFS technology into Linux, because it is licensed under Sun's Common Development and Distribution License (CDDL), which is incompatible with GPL v2. AdvFS matches several key ZFS features, and as Linux developers embrace AdvFS technology, it will become more feasible to offer Open Storage solutions based on standard Linux distributions, whereby solution providers add value with various data services (copy, replication, de-duplication, thin provisioning) on top of standard interfaces in the Linux kernel. By becoming fully engaged with efforts to enable Linux for open storage at the earliest stages, HP can start to position itself in a leadership role should open storage solutions start to generate serious momentum in the market.