Date: Fri, 8 Jan 2010 16:23:03 -0500 From: "Jonathan Noack" <noackjr@alumni.rice.edu> To: "Garrett Moore" <garrettmoore@gmail.com> Cc: freebsd-stable@freebsd.org Subject: Re: ZFS performance degradation over time Message-ID: <a1e355586b0e697490159a4733f94988.squirrel@www.noacks.org> In-Reply-To: <7346c5c61001080831w375d158fu5b1996ee58cb0f8d@mail.gmail.com> References: <7346c5c61001030842r7dc76199y51e4c1c90a3eea6e@mail.gmail.com> <hi2nsf$do5$1@ger.gmane.org> <7346c5c61001080831w375d158fu5b1996ee58cb0f8d@mail.gmail.com>
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On Fri, January 8, 2010 11:31, Garrett Moore wrote: > No, I haven't isolated the cause to only be uptime related. In my original > email I mentioned that "as suggested by someone in the thread, it's > probably > not directly related to system uptime, but instead related to usage - the > more usage, the worse the performance." > > I've been starting my system with different combinations of applications > running to see what access patterns cause the most slowdown. So far, I > don't > have enough data to give anything concrete. > > This weekend I'll try some tests such as the one you describe, and see > what > happens. I have a strong suspicion that rTorrent is to blame, since I > haven't seen major slowdowns in the last few days with rTorrent not > running. > rTorrent preallocates the space needed for the file download (and I'm > downloading large 4GB+ files using it), and then writes to them in an > unpredictable pattern, so maybe ZFS doesn't like being touched this way? Probably unrelated, but this prefetch issue results in a slowdown: http://lists.freebsd.org/pipermail/freebsd-fs/2009-December/007481.html -Jonathan
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