PERC4/Di Per-disk IO counters

[Mark Dadgar]

On Jun 27, 2006, at 8:13 PM, Matt Domsch wrote:
> Per physical disk isn't terribly interesting.  Even if you want to see
> how badly mixing different spindle speeds in the same logical drive
> affects its performance, you're still wanting to measure performance
> of the LD, not each PD.

That's actually not entirely true.  It can be useful for diagnosing  
performance issues where a single drive in a stripe is getting  
hammered because you chose a stripe size that is inappropriate for  
your IO mix and/or application behaviour.

Otherwise, I'd agree that LD performance is a much more interesting  
statistic in the general case.

- Mark, SE for the first network-attached storage company in a past life
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