Ending out our tests we had the PostMark test where the performance of the ZFS Linux kernel module done by KQ Infotech and the Lawrence Livermore National Laboratories was slaughtered. The disk transaction performance for ZFS on this native Linux kernel module was even worse than using ZFS-FUSE and was almost at half the speed of this test when run under the OpenSolaris-based OpenIndiana distribution. EXT4, Btrfs, and XFS were all at least ten times as fast as ZFS on Linux.
While it is nice to see a native Linux kernel module for the ZFS file-system functioning on Linux, it is not perfect. Besides the fact that it will have to live outside of the mainline Linux kernel due to license incompatibilities, and the implications that it brings, it is also dependent upon the Solaris Porting Layer (SPL) modules for emulating some Solaris kernel functionality within the Linux kernel. There is also the matter of this working ZFS kernel module not being publicly available from KQ Infotech for another two months and we do not know what the future will hold for this company's efforts in supporting ZFS on Linux. At least the Lawrence Livermore National Laboratories will likely be pulling some of the KQ Infotech changes upstream into their supported, open-source project.
In terms of our ZFS on Linux benchmarks, if you have desired this Sun-created file-system on Linux, hopefully it is not because of the performance expectations for this file-system. As these results illustrate, this ZFS file-system implementation for Linux is not superior to the Linux popular file-systems like EXT4, Btrfs, and XFS. There are a few areas where the ZFS Linux disk performance was competitive, but overall it was noticeably slower than the big three Linux file-systems in a common single disk configuration. That though is not to say ZFS on Linux will be useless as the performance is at least acceptable and clearly superior to that of ZFS-FUSE. More importantly, there are a number of technical merits to the ZFS file-system that makes it one of the most interesting file-systems around.
When KQ Infotech releases these ZFS packages to the public in January and rebases them against a later version of ZFS/Zpool, we will publish more benchmarks.
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