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From Ted Yu <yuzhih...@gmail.com>
Subject Re: Canary Test Tool and write sniffing
Date Sat, 04 Feb 2017 16:00:16 GMT
For the default interval , if you were looking at:

  private static final long DEFAULT_INTERVAL = 6000;

The above was from:

    HBASE-4393 Implement a canary monitoring program

which was integrated on Tue Apr 24 07:20:16 2012

FYI

On Sat, Feb 4, 2017 at 4:06 AM, Lars George <lars.george@gmail.com> wrote:

> Also, the default interval used to be 60 secs, but is now 6 secs. Does
> that make sense? Seems awfully short for a default, assuming you have
> many regions or servers.
>
> On Sat, Feb 4, 2017 at 11:54 AM, Lars George <lars.george@gmail.com>
> wrote:
> > Hi,
> >
> > Looking at the Canary tool, it tries to ensure that all canary test
> > table regions are spread across all region servers. If that is not the
> > case, it calls:
> >
> > if (numberOfCoveredServers < numberOfServers) {
> >   admin.balancer();
> > }
> >
> > I doubt this will help with the StochasticLoadBalancer, which is known
> > to consider per-table balancing as one of many factors. In practice,
> > the SLB will most likely _not_ distribute the canary regions
> > sufficiently, leaving gap in the check. Switching on the per-table
> > option is discouraged against to let it do its thing.
> >
> > Just pointing it out for vetting.
> >
> > Lars
>

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