Linked by diegocg on Thu 7th Nov 2013 22:19 UTC
Linux Linux kernel 3.12 has been released. This release includes support for offline deduplication in Btrfs, automatic GPU switching in laptops with dual GPUs, a performance boost for AMD Radeon graphics, better RAID-5 multicore performance, improved handling of out-of-memory situations, improvements to the timerless multitasking mode, separate modesetting and rendering device nodes in the graphics DRM layer, improved locking performance for virtualized guests, XFS directory recursion scalability improvements, new drivers and many small improvements. Here's the full list of changes.
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RE[4]: Btrfs dedup
by Alfman on Fri 8th Nov 2013 23:12 UTC in reply to "RE[3]: Btrfs dedup"
Member since:


"I have been running ZFS on Linux boxes with standard kernels for over a year. Using the ZFS kernel module (or ZFS-FUSE) does not require a custom kernel."

Thanks for the suggestion. The problem with fuse is that it doesn't offer good performance. In some benchmarks, Fuse-ZFS barely registers on the chart.

This link is somewhat dated, but it's never the less been my experience that ALL fuse filesystems suffer from excessively high CPU utilization and low performance, particularly under high concurrency, and the benchmarks here bear that out. I find it unlikely that a recent benchmark would be any kinder to Fuse-ZFS. I may be convinced to go with ZFS, but if I do it will definitely be a patched kernel. That's not to say fuse-zfs isn't useful for it's features, it would just defeat the point in my having a high performance raid array.

Btrfs is also compared in the link above for anyone interested (I wouldn't be surprised if it has improved since 2010).

Edited 2013-11-08 23:13 UTC

Reply Parent Score: 2

RE[5]: Btrfs dedup
by phoenix on Sat 9th Nov 2013 00:09 in reply to "RE[4]: Btrfs dedup"
phoenix Member since:

He said to use the ZFSonLinux kernel modules, not FUSE modules. Several distro now include ZFSonLinux packages in their repos, and more are available on their website. No custom kernel required, and no loss of performance due to FUSE.

Reply Parent Score: 4

RE[6]: Btrfs dedup
by Alfman on Sat 9th Nov 2013 07:17 in reply to "RE[5]: Btrfs dedup"
Alfman Member since:


Thanks for pointing that out, somehow I focused only on ZFS-Fuse. I do not see ZFS kernel modules being supported natively by Debian, mint, centos, and I presume ubuntu, do any distros carry it natively?

I did see that has modules for many popular distros (ie dep for debian, rpm for cent), but that's still technically the kind of 3rd party code/binary modules that I was trying to avoid. For those who don't mind this, then they can (and should) go this route. However let me just mention my own reasons for hesitating with this solution:

1. I believe I may be in violation of the CDDL & GPL licenses if I redistributed a kernel with ZFS to my clients.

It's nearly inconceivable my clients would actually notice, much less care. I really have no idea if the copyright holders would care in the slim chance they got wind of it (ie oracle or linux devs). Maybe they wouldn't, but it'd still bug me if *my* business was in violation, you know?

2. My previous experiences with 3rd party modules (source & binaries) is that every single kernel update has the potential to break the 3rd party kernel code. The result means that module developers must keep on top of each and every mainline release (if distributing source), and each and every distro release (if distributing binaries), in order to not leave a gap in supported kernels. It wouldn't be the first time I've had to get my hands into the code to fix a temporary incompatibility with new kernels.

In fairness to zfsonlinux, I'm NOT pointing a finger at them, it's just an inherent problem with the kernel lacking a stable API/ABI. I may very well go with ZFS to gain it's functionality, but honestly using it as a root file system would make me nervous every time I upgraded the kernel on a server. I don't have this nervousness with say EXT4, so I'd probably keep root as an ext4 partition until ZFS is in mainline or if the ZFS kernel modifications were officially supported by the distro.

Edited 2013-11-09 07:34 UTC

Reply Parent Score: 3