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From Tupshin Harper <tups...@tupshin.com>
Subject Re: Setting up DSE 4.5 for mixed workload with BYOH
Date Thu, 03 Jul 2014 01:10:59 GMT
Yes.  It greatly increases the splits and the random io.

-Tupshin
On Jul 2, 2014 6:09 PM, "Clint Kelly" <clint.kelly@gmail.com> wrote:

> Sorry BTW in case what I wrote below is unclear, is the concern that
> the Hadoop InputFormat (as an example) will need to have a separate
> InputSplit (which corresponds to a "SELECT foo FROM bar WHERE
> token(baz) > min AND token(baz) < max") for every vnode instead of for
> every token?
>
> (I assume this would be an increase of several orders of magnitude in
> the number of input splits.)
>
> Best regards,
> Clint
>
> On Wed, Jul 2, 2014 at 6:04 PM, Clint Kelly <clint.kelly@gmail.com> wrote:
> > Hi Tupshin,
> >
> > Thanks for the quick reply.  Is the performance concern from the
> > Hadoop integration needing to set up separate SELECT operations for
> > all of the unique vnode ranges?
> >
> > Best regards,
> > Clint
> >
> > On Wed, Jul 2, 2014 at 6:00 PM, Tupshin Harper <tupshin@tupshin.com>
> wrote:
> >> For performance reasons, you shouldn't enable vnodes on any
> Cassandra/DSE
> >> datacenter that is doing hadoop analytics workloads.  Other DCs in the
> >> cluster can use vnodes.
> >>
> >> -Tupshin
> >>
> >> On Jul 2, 2014 5:50 PM, "Clint Kelly" <clint.kelly@gmail.com> wrote:
> >>>
> >>> Hi everyone,
> >>>
> >>> Apologies if this is the incorrect forum for a question like this.
> >>>
> >>> I am going to set up a mixed-workload (real-time and analytics)
> >>> installation of DSE 4.5 using bring-your-own Hadoop (BYOH).  We are
> >>> using CDH 5.0.
> >>>
> >>> I was reviewing the installation instructions, and I came across the
> >>> following comment here:
> >>>
> >>>
> http://www.datastax.com/documentation/datastax_enterprise/4.5/datastax_enterprise/byoh/byohInstall.html
> >>>
> >>> "6. Observe workload isolation best practices. Do not enable vnodes."
> >>>
> >>> Does this mean that the use of vnodes is not compatible with a
> >>> mixed-workload installation?  Or with BYOH?  I am confused why this
> >>> would be the case.
> >>>
> >>> If anyone can clarify, I would greatly appreciate it.
> >>>
> >>> Best regards,
> >>> Clint
>

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