Re: What's the best hardver for PostgreSQL 8.1?

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At 04:15 PM 12/27/2005, Michael Stone wrote:
I don't understand why you keep using the pejorative term "performance
hit". Try describing the "performance characteristics" instead.

pe·jor·a·tive    ( P )  Pronunciation Key  (p-jôr-tv, -jr-, pj-rtv, pj-)
adj.
Tending to make or become worse.
Disparaging; belittling.

RAID 5 write performance is significantly enough less than RAID 5 read performance as to be a matter of professional note and concern. That's not "disparaging or belittling" nor is it "tending to make or become worse". It's measurable fact that has an adverse impact on capacity planning, budgeting, HW deployment, etc.

If you consider calling a provable decrease in performance while doing a certain task that has such effects "a hit" or "bad" pejorative, you are using a definition for the word that is different than the standard one.


Also, claims about performance claims based on experience are fairly useless.
Either you have data to provide (in which case claiming vast experience
is unnecessary) or you don't.

My experience _is_ the data provided. Isn't it convenient for you that I don't have the records for every job I've done in 20 years, nor do I necessarily have the right to release some specifics for some of what I do have. I've said what I can as a service to the community. Including to you. Your reaction implies that I and others with perhaps equally or more valuable experience to share shouldn't bother.

"One of the major differences between Man and Beast is that Man learns from others experience."

It's also impressive that you evidently seem to be implying that you do such records for your own job experience _and_ that you have the legal right to publish them. In which case, please feel free to impress me further by doing so.


Said RAID 10 array will also be more robust than a RAID 5 built using the same number of HDs.

And a RAID 6 will be more robust than either. Basing reliability on
"hopefully you wont have both disks in a mirror fail" is just silly.
Either you need double disk failure protection or you don't.
That statement is incorrect and ignores both probability and real world statistical failure patterns.

The odds of a RAID 10 array of n HDs suffering a failure that loses data are less than the odds of it happening in a RAID 6 array of n HDs. You are correct that RAID 6 is more robust than RAID 5.

cheers,
Ron




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