ZFS performance bottlenecks: CPU or RAM or anything else?

[Matthew D. Fuller]

On Tue, May 17, 2016 at 02:16:16PM -0700 I heard the voice of
Freddie Cash, and lo! it spake thus:
> 
> They're not asking for ways to improve the performance of a
> raidz-based pool; they're asking why they get different performance
> metrics from the exact same pool when they change the CPU and RAM.

More specifically, as I read it, different performance in a very
specific metric; single-thread linear bulk writes.  That doesn't seem
like it would benefit heavily from a lot of cores available, or from
RAM bandwidth or size above a pretty low threshold.

Of course, it's not just changing the CPU and RAM; it's also the
motherboard, and possibly the HBA (at least the bus the HBA is on, if
it's a card being transplanted with the pool).  And the Core 2 would
be back in the plain-old FSB era, so RAM access would be competing
with the disk IO on the bus.


-- 
Matthew Fuller     (MF4839)   |  fullermd at over-yonder.net
Systems/Network Administrator |  http://www.over-yonder.net/~fullermd/
           On the Internet, nobody can hear you scream.