NFSv3, ZFS, 10GE performance

[Bob Friesenhahn]

On Mon, 26 Mar 2012, Sven Brandenburg wrote:
>
>> Are you only interested in single threaded read performance to a single
>> client?
> My first item on the list is serving one client as fast as possible, next 
> step is multiple client machines (maybe these are conflicting goals?). 
> However, I figure that I should at least be able to press the right buttons 
> to dial in "fast" for one client :-)

It really depends on if the client will actually consume all of the 
data as requested or if the client application will be competing with 
NFS because it transfers data it will never need.

An issue which is quite familiar to me is the TIFF image file format. 
This format stores the image data in sequential strips, yet it uses 
more complex data structures (which require many seek + small read) as 
well.  In my testing, I found that excessive read-ahead hindered 
performance with this file format.  More than 16k of read-ahead often 
resulted in a performance penalty over NFS.

Memory mapped files can also cause a performance problem since the MMU 
page size is typically 4K and the program is blocked from running 
until the current page fault completes.

Bob
-- 
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/