A bottleneck in gstripe?

Ivan Voras ivoras at fer.hr
Sat Feb 17 23:38:45 UTC 2007

Kirk Strauser wrote:
> I built a gstripe volume with 4 drives and a 128KB stripesize.  When running 
> one particular application, gstat reports that stripe/stripe1 is 99% busy, 
> although its four drives are running at less than 30% each.  Am I 
> misinterpreting the numbers - maybe the total is the sum of the drives? - 
> or is there some giant overhead that I'm missing?

Nevermind the "% used" number, it's an approximation of an approximation
- how is your real world performance? For example, use
ports/benchmarks/bonnie++ .

> I've set kern.geom.stripe.fast=1, and kern.geom.stripe.fast_failed stays at 
> 0.  I don't have enough experience with geom_strip to even know where to go 
> from here.  Are stripe sizes likely to make much of a difference when the 
> heaviest load is when PostgreSQL is receiving massive imports?  This is a 

Not much, as the data is first written to WAL, which goes at full file
system speed (no fsyncs).

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