Well, a typical conversation about speed and stability usually boils down to this:A: I've heard that XYZ is unstable and slow. B: Are you sure? Have you tested XYZ? What are your benchmark results? Have you had any issues? A: No. I *have* *not* *tested* XYZ. I think XYZ is so unstable and slow that it's not worth testing.Yes indeed! I can't afford to test everything carefully. Like most people, I read published reports and listen to conversations places like this, and form an impression of what performs how. Then I do some testing to verify that something I'm seriously considering produces satisfactory performance. The key there is "satisfactory"; I'm not looking for the "best", I'm looking for something that fits in and is satisfactory. The more unusual my requirements, and the better defined, the less I can gain from studying outside test reports.
My only point was: There is no published report saying that stability or *performance* of Btrfs will be worse (or better) than that of ZFS. This is because nobody can guess how Btrfs will perform once it's finished. (In fact nobody even knows *when* it is going to be finished. My guess was that it might not be considered "experimental" in one year's time, but that's just a shot in the dark.) For that reason, spreading myths about "stability & performance & maturity" serves no purpose. (And this is what caused my (over)reaction.) I did not say there is something wrong about published reports. I often read them. (Who doesn't?) However, there are no trustworthy reports on this topic yet, since Btrfs is unfinished. Let's see some examples: (1) http://www.phoronix.com/scan.php?page=article&item=zfs_ext4_btrfs&num=1 (2) http://www.dhtusa.com/media/IOPerf_CMG09DHT.pdf Based on (1), one could say that Btrfs outperforms ZFS with ease and confidence. Unfinished Btrfs versus a port of ZFS to FreeBSD -- that sounds fair, doesn't it? Well, in fact such a "comparison" is neither fair nor meaningful. Furthermore, benchmarks from Phoronix don't seem to have a good reputation... (See the P. S. for details.) In (2), ZFS performs (much) better than (what will once be) Btrfs. However, the results in (2) are related to a 2.6.30 kernel, which is as *old* as June 2009... Nobody knows how the tested file systems would perform today. Yes, Btrfs is still somewhat immature. Yes, Btrfs is not ready for serious deployments (right now, in August 2010). So it's way to soon to compare the stability and performance of Btrfs and ZFS. Disclaimer: I use Reiser4, Ext4, ZFS, Btrfs and Ext3 (in this order of frequency) and I'm not an advocate of any of them. Andrej P. S. As far as Phoronix is concerned... Well, I remember how they once used a malfunctioning and crippled Reiser4 implementation (hacked by the people around the ZEN patchset so that it caused data corruption (!) and kernel crashes) and "compared" it to other file systems. (That foolish Reiser4 "benchmark" can be found here: http://www.phoronix.com/scan.php?page=article&item=reiser4_benchmarks&num=1)
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