[Gluster-users] How gluster parallelize reads

Jeff Darcy jdarcy at redhat.com
Mon Oct 3 18:48:03 UTC 2016

> > 0 means use the first server to respond I think - at least that's my guess
> > of what "first up server" means
> > 1 hashed by GFID,  so clients will use the same server for a given file but
> > different files may be accessed from different nodes.
> I think that 1 is better.
> Why "0" is the default ?

Basic storage-developer conservatism.  Zero was the behavior before
read-hash-mode was implemented.  As strongly as some of us might believe
that such tweaks lead to better behavior - as I did with this one in
2012[1] - we've kind of learned the hard way that existing users often
disagree with our estimations.  Thus, new behavior is often kept as a
"special" for particular known environments or use cases, and the
default is left unchanged until there's clear feedback indicating it
should be otherwise.

[1] http://review.gluster.org/#/c/2926/

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