[Discuss] SSD: enterprise vs. consumer Flash

[tmetro+blu at gmail.com (Tom Metro)]

Richard Pieri wrote:
> There ain't no such thing as "high end" flash chips in the way that
> you're thinking.  High end in the NAND flash arena is a matter of
> sustained write performance.  That's it.  Not quality.  Not reliability.
> Speed.

Hmmm...that's *exactly* the way that I was thinking. Earlier in this
thread I wrote, "...it seems likely that the mid-range SSDs are going to
be using higher density chips, with faster write speeds, both of which
will lead to lower production yields and thus higher prices."


> The thing is, flash read and write speeds have a technical
> plateau so you won't see much difference in the raw performance of
> different manufacturers' chips of a given generation.

I'll buy that, but I'm still skeptical that a $20 USB drive has the same
chips in it as a $200 SSD, let alone a $1000 SSD.


> The difference is how different vendors optimize their controllers.

Makes sense.


> So how do the likes of EMC and Violin go so much faster for so much
> longer (5-10 years vs. 6-24 months for commodity SSD)?  Several things.
> They use battery-backed DRAM cache on their controllers.

So more silicon...


> The typical consumer-grade SSD has a single big flash chip in it.  An
> enterprise class SSD has banks of chips arranged in something similar to
> a RAID 0 configuration to reap the benefits of more "spindles".

So more chips...


> Enterprise-class SSDs can have 100-200% over-provisioning or more.

So more silicon...


> All of this comes at a premium.

Yes, these are all plausible reasons for why an enterprise SSD costs
more than a consumer SSD. But the situation you described is a far cry
from the scenario Ed suggested where the exact same type and quantity of
Flash chips simply have a different controller chip added and it doubles
or triples the price. That was the bit I was skeptical of.

Thanks for the additional detail.

 -Tom

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/