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Subject: Re: ZFS performance degradation over time
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On 3.1.2010 17:42, Garrett Moore wrote:

> I'm having problems with ZFS performance. When my system comes up,
> read/write speeds are excellent (testing with dd if=/dev/zero
> of=/tank/bigfile and dd if=/tank/bigfile of=/dev/null); I get at least
> 100MB/s on both reads and writes, and I'm happy with that.
> 
> The longer the system is up, the worse my performance gets. Currently my
> system has been up for 4 days, and read/write performance is down to about
> 10MB/s at best.

Are you sure you have isolated the cause to be only the uptime of the
machine? Is there no other change between the runs? E.g. did you stop
all other services and applications on the machine before doing the test
for the second time? Can you create a big file (2x memory size) when the
machine boots, measure the time to read it, then read it again after a
few days when you notice performance problems?