Re: Intel SRCS16 SATA raid? (somewhat OT)

От: Marinos Yannikos
Тема: Re: Intel SRCS16 SATA raid? (somewhat OT)
Дата: ,
Msg-id: 425FE8F3.5010604@geizhals.at
(см: обсуждение, исходный текст)
Ответ на: Re: Intel SRCS16 SATA raid?  (Alex Turner)
Список: pgsql-performance

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Intel SRCS16 SATA raid?  (Greg Stark, )
 Re: Intel SRCS16 SATA raid?  ("Mohan, Ross", )
  Re: Intel SRCS16 SATA raid?  ("Joshua D. Drake", )
   Re: Intel SRCS16 SATA raid?  (Marinos Yannikos, )
    Re: Intel SRCS16 SATA raid?  (Alex Turner, )
     Re: Intel SRCS16 SATA raid? (somewhat OT)  (Marinos Yannikos, )
 Re: Intel SRCS16 SATA raid?  (, )
  Re: Intel SRCS16 SATA raid?  (Alex Turner, )
   Re: Intel SRCS16 SATA raid?  (Alex Turner, )
    Re: Intel SRCS16 SATA raid?  (, )
  Re: Intel SRCS16 SATA raid?  (Bruce Momjian, )
 Re: Intel SRCS16 SATA raid?  ("Dave Held", )
  Re: Intel SRCS16 SATA raid?  (Alex Turner, )
  Re: Intel SRCS16 SATA raid?  (Alex Turner, )
   Re: Intel SRCS16 SATA raid?  (Geoffrey, )
 Re: Intel SRCS16 SATA raid?  ("Dave Held", )
  Re: Intel SRCS16 SATA raid?  (, )
  Re: Intel SRCS16 SATA raid?  (Alex Turner, )
   Re: Intel SRCS16 SATA raid?  (, )
   Re: Intel SRCS16 SATA raid?  (Vivek Khera, )
    Re: Intel SRCS16 SATA raid?  (Alex Turner, )
 Re: Intel SRCS16 SATA raid?  ("Dave Held", )

Alex Turner wrote:
> No offense to that review, but it was really wasn't that good, and
> drew bad conclusions from the data.  I posted it originaly and
> immediately regretted it.
>
> See http://www.tweakers.net/reviews/557/18
>
> Amazingly the controller with 1Gig cache manages a write throughput of
> 750MB/sec on a single drive.
>
> quote:
> "Floating high above the crowd, the ARC-1120 has a perfect view on the
> struggles of the other adapters. "
>
> It's because the adapter has 1Gig of RAM, nothing to do with the RAID
> architecture, it's clearly caching the entire dataset.  The drive
> can't physicaly run that fast.  These guys really don't know what they
> are doing.

Perhaps you didn't read the whole page. It says right at the beginning:

"Because of its simplicity and short test duration, the ATTO Disk
Benchmark is used a lot for comparing the 'peformance' of hard disks.
The tool measures the sequential transfer rate of a partition using a
test length of 32MB at most. Because of this small dataset, ATTO is
unsuitable for measuring media transfer rates of intelligent
RAID-adapters which are equipped with cache memory. The smart RAID
adapters will serve the requested data directly from their cache, as a
result of which the results have no relationship to the media transfer
rates of these cards. For this reason ATTO is an ideal tool to test the
cache transfer rates of intelligent RAID-adapters."

Therefore, the results on this page are valid - they're supposed to show
the cache/transfer speed, the dataset is 32MB(!) and should fit in the
caches of all cards.

> See also:
> http://www20.tomshardware.com/storage/20041227/areca-raid6-06.html
>
> I trust toms hardware a little more to set up a good review to be honest.

I don't, for many (historical) reasons.

> The 3ware trounces the Areca in all IO/sec test.

Maybe, but with no mention of stripe size and other configuration
details, this is somewhat suspicious. I'll be able to offer benchmarks
for the 8506-8 vs. the 1120 shortly (1-2 weeks), if you're interested
(pg_bench, for example, to be a bit more on-topic).

Regards,
  Marinos


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