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Date: Tue, 23 Feb 2010 20:34:58 +0100
From: Bernd Walter <ticso@cicely7.cicely.de>
To: Ivan Voras <ivoras@freebsd.org>
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Cc: freebsd-fs@freebsd.org
Subject: Re: Some ZFS+NFS benchmarks (OpenSolaris)
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On Tue, Feb 23, 2010 at 08:15:48PM +0100, Ivan Voras wrote:
> http://staff.science.uva.nl/~delaat/sne-2009-2010/p02/report.pdf
> 
> It's curious how ZIL on SSD doesn't help them with NFS when they 
> increase the load.

My assumption is because they already write linear on SSD and get a more
or less fixed write rate, while parallel write rate with disks can
increase because of reordering.

I'm personally impressed by my own tests on how much our current
USB stack can speed up random reads even with cheap USB flash sticks
used as cache devices.
While it is true that a SSD is much faster it is also true for me that
the bigger capacity of same price USB sticks can be a better win.
Especially working with svn and CVS trees get a lot of performance
from high ARC2 hit rate.

One bad thing about large capacity is that my system currently boots
with empty cache devices.
In some documents they talk that cache content is held over reboots.
Is this just future work in ZFS, future work with FreeBSD, or is my
system just a few months too old?

-- 
B.Walter <bernd@bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.