Re: SCSI vs SATA - Mailing list pgsql-performance

At 11:40 PM 4/5/2007, david@lang.hm wrote:
>On Thu, 5 Apr 2007, Ron wrote:
>
>>At 10:07 PM 4/5/2007, david@lang.hm wrote:
>>>On Thu, 5 Apr 2007, Scott Marlowe wrote:
>>> > Server class drives are designed with a longer lifespan in mind.
>>> > > Server class hard drives are rated at higher temperatures than desktop
>>> > drives.
>>>these two I question.
>>>David Lang
>>Both statements are the literal truth.  Not that I would suggest
>>abusing your server class HDs just because they are designed to
>>live longer and in more demanding environments.
>>
>>Overheating, nasty electrical phenomenon, and abusive physical
>>shocks will trash a server class HD almost as fast as it will a
>>consumer grade one.
>>
>>The big difference between the two is that a server class HD can
>>sit in a rack with literally 100's of its brothers around it,
>>cranking away on server class workloads 24x7 in a constant
>>vibration environment (fans, other HDs, NOC cooling systems) and be
>>quite happy while a consumer HD will suffer greatly shortened life
>>and die a horrible death in such a environment and under such use.
>
>Ron,
>   I know that the drive manufacturers have been claiming this, but
> I'll say that my experiance doesn't show a difference and neither
> do the google and CMU studies (and they were all in large
> datacenters, some HPC labs, some commercial companies).
>
>again the studies showed _no_ noticable difference between the
>'enterprise' SCSI drives and the 'consumer' SATA drives.
>
>David Lang
Bear in mind that Google was and is notorious for pushing their
environmental factors to the limit while using the cheapest "PoS" HW
they can get their hands on.
Let's just say I'm fairly sure every piece of HW they were using for
those studies was operating outside of manufacturer's suggested specifications.

Under such conditions the environmental factors are so deleterious
that they swamp any other effect.

OTOH, I've spent my career being as careful as possible to as much as
possible run HW within manufacturer's suggested specifications.
I've been chided for it over the years... ...usually by folks who
"save" money by buying commodity HDs for big RAID farms in NOCs or
push their environmental envelope or push their usage envelope or ...
...and then act surprised when they have so much more down time and
HW replacements than I do.

All I can tell you is that I've gotten to eat my holiday dinner far
more often than than my counterparts who push it in that fashion.

OTOH, there are crises like the Power Outage of 2003 in the NE USA
where some places had such Bad Things happen that it simply doesn't
matter what you bought
(power dies, generator cuts in, power comes on, but AC units crash,
temperatures shoot up so fast that by the time everything is
re-shutdown it's in the 100F range in the NOC.  Lot's 'O Stuff dies
on the spot + spend next 6 months having HW failures at
+considerably+ higher rates than historical norms.  Ick..)

  IME, it really does make a difference =if you pay attention to the
difference in the first place=.
If you treat everything equally poorly, then you should not be
surprised when everything acts equally poorly.

But hey, YMMV.

Cheers,
Ron Peacetree