ZFS

It’s Here. The March 2018 Issue of Linux Journal Is Available for Download Now.

Carlie Fairchild — Tue, 13 Mar 2018 15:08:24 +0000

Boasting as many pages as most technical books, this month’s issue of Linux Journal comes in at a hefty 181—that’s 23 articles exploring topics near and dear to everyone from home automation hobbyists to Free Software advocates to hard-core hackers to high-level systems architects.

Besides making the magazine bigger overall with more articles in each issue on a wider range of topics, we’ve also added a new feature that explores a given topic in-depth: the Deep Dive—think of it like an ebook inside each magazine. This month contributing editor Petros Koutoupis dives deep in to blockchain. He explores what makes Bitcoin and blockchain so exciting, what they provide, and what the future of blockchain holds. From there, he describes how to set up a private Etherium blockchain using open-source tools and looks at some markets and industries where blockchain technologies can add value.

Subscribers, you can download your March issue now.

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ZFS for Linux

Charles Fisher — Mon, 12 Feb 2018 15:54:56 +0000

by Charles Fisher

Presenting the Solaris ZFS filesystem, as implemented in Linux FUSE, native kernel modules and the Antergos Linux installer.

ZFS remains one of the most technically advanced and feature-complete filesystems since it appeared in October 2005. Code for Sun's original Zettabyte File System was released under the CDDL open-source license, and it has since become a standard component of FreeBSD and slowly migrated to various BSD brethren, while maintaining a strong hold over the descendants of OpenSolaris, including OpenIndiana and SmartOS.

Oracle is the owner and custodian of ZFS, and it's in a peculiar position with respect to Linux filesystems. Btrfs, the main challenger to ZFS, began development at Oracle, where it is a core component of Oracle Linux, despite stability issues Red Hat's recent decision to deprecate Btrfs likely introduces compatibility and support challenges for Oracle's Linux road map. Oracle obviously has deep familiarity with the Linux filesystem landscape, having recently released "dedup" patches for XFS. ZFS is the only filesystem option that is stable, protects your data, is proven to survive in most hostile environments and has a lengthy usage history with well understood strengths and weaknesses.

ZFS has been (mostly) kept out of Linux due to CDDL incompatibility with Linux's GPL license. It is the clear hope of the Linux community that Oracle will re-license ZFS in a form that can be included in Linux, and we should all gently cajole Oracle to do so. Obviously, a re-license of ZFS will have a clear impact on Btrfs and the rest of Linux, and we should work to understand Oracle's position as the holder of these tools. However, Oracle continues to gift large software projects for independent leadership. Incomplete examples of Oracle's largesse include OpenOffice and recently Java Enterprise Edition, so it is not inconceivable that Oracle's generosity may at some point extend additionally to ZFS.

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ZFS: Finding Its Way to a Linux Near You?

Petros Koutoupis — Wed, 01 Jun 2016 18:00:00 +0000

by Petros Koutoupis

It seems like only yesterday that I read Jeff Bonwick's blog entry "ZFS: The Last Word in Filesystems". It was Halloween of 2005 that ZFS was fully integrated into Sun Microsystem's Solaris, and the filesystem was very well received. For the readers not familiar with ZFS, it is a combined all-purpose filesystem and volume manager. It simplified data storage management while also offering the most advanced features of the time. Such technologies include drive pooling with software RAID support, file snapshots, in-line data compression, data deduplication, built-in data integrity, advanced caching (to DRAM and SSD), and more. Today, the ZFS trademark and technology is owned and maintained by the Oracle Corporation.

Also in 2005, Sun Microsystems introduced OpenSolaris. Now a defunct project, OpenSolaris was a fully functional Solaris operating system built entirely from open source, which included ZFS, and all of which were re-licensed to the Common Development and Distribution License (CDDL), a weak copyleft license based on the Mozilla Public License (MPL). Although open source, ZFS and anything else under the CDDL was, and supposedly still is, incompatible with the GNU General Public License (GPL). This includes the Linux kernel and eventually would lead to the birth of Btrfs.

To avoid licensing infringements, the earliest incarnations of ZFS on Linux were written for the Filesystem in Userspace (FUSE). This prevented the technology from touching the Linux kernel. It also added its fair share of limitations. Being in userspace, it never could really measure up to its Solaris and FreeBSD counterparts. Over time, some of the FUSE implementations were highly neglected and in some cases abandoned. In 2008, the "ZFS on Linux" project changed everything by developing an in-kernel implementation of ZFS. Since its conception, the project was met with a lot of resistance (and criticism) from within the Linux community, all relating to licensing.

Fast-forward to the present, and two distributions have challenged this. Last month, Canonical, the parent company of the Ubuntu Linux distribution released the latest Ubuntu 16.04, codenamed Xenial Xerus. One of the most noteworthy additions to this release was the full integration of pre-built ZFS modules. Although Canonical now ships Ubuntu with ZFS, it has publicly stated that its legal team did not see a violation of the GPL. This matter is still being debated.

Shortly following this news and through a separate and completely unrelated effort, the Debian distribution announced the inclusion of the ZFS source code, buildable via the Dynamic Kernel Module Support (DKMS) framework. However, it is not provided in the "main" section archive but instead in "contrib". Under the legal advice of the Software Freedom Law Center, this approach is seen as not violating the GPL license.

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