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HBase >> mail # dev >> gauging cost of region movement

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RE: gauging cost of region movement
Also, using more stable measures of request count will help, such as 30 minute rolling averages.

> -----Original Message-----
> From: Jonathan Gray [mailto:[EMAIL PROTECTED]]
> Sent: Monday, March 21, 2011 4:23 PM
> Subject: RE: gauging cost of region movement
> This is an interesting direction, and definitely file a JIRA as this could be an
> additional metric in the future, but it's not exactly what I had in mind.
> One of the hardest parts of load balancing based on request count and other
> dynamic/transient measures is that you can get some pretty pathological
> conditions where you are always moving stuff around.
> To guard against it, I think we'll need to move to more of a cost-based
> algorithm that is taking not just the difference in request counts into account
> but also a baseline "cost" of moving a region.  The cost difference in load
> between two unbalanced servers would have to outweigh the cost
> associated with moving a region.  As you say, looking at the number of live
> operations to a given region could contribute to the cost of moving that
> region, but the best measure for that is probably just looking at request
> count (it's all requests that incur a cost, not just active scanners).
> JG
> > -----Original Message-----
> > From: Ted Yu [mailto:[EMAIL PROTECTED]]
> > Sent: Monday, March 21, 2011 3:44 PM
> > Subject: gauging cost of region movement
> >
> > Can we add a counter for the number of InternalScanner's to HRegion ?
> > We decrement this counter when close() is called.
> >
> > Such counter can be used to gauge the cost of moving the underlying
> region.
> >
> > Cheers