Brian Hechinger wrote:
On Fri, Jul 28, 2006 at 02:02:13PM -0700, Richard Elling wrote:
Joseph Mocker wrote:
Richard Elling wrote:
The problem is that there are at least 3 knobs to turn (space, RAS, and
performance) and they all interact with each other.
Good point. then how about something more like
zpool bench raidz favor space disk1 ... diskN
zpool bench raidz favor performance disk1 .. diskN
That is, tell the analyzer which knob you are most interested in.
I wish it was that easy. If I optimize for space, I'll always get a big,
fat RAID-0. If I optimize for RAS, I'll get multi paned (N-way) mirror.
The tool has to be able to handle the spectrum in between those extremes.
Look closer at the format of that command:
zpool bench *RAIDZ* blah....
RAID-0 isn't an option, find the best parameters for what is specified,
in this case we are constrained to RAIDZ.
Given N disks, what is the best raidz configuration is also not a
trivial question to answer. The spectrum is narrowed to something
between N-way and (int)N/3 3-way plus at least one spare.
-- richard
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