On Sun, Jun 3, 2012 at 10:55 PM, Tom Metro <tmetro+...@gmail.com> wrote: > 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
When you have a chance, if you haven't seen it already, check out the videos on youtube by Scott Moulton, aka SuperFlyflippingA. He is a Digital Forensics and hard drive expert, and his videos will provide great details on the inner-workings of both mechanical and SSD drives, along with how chip selection is managed by the vendors. Scott > > -- > Tom Metro > Venture Logic, Newton, MA, USA > "Enterprise solutions through open source." > Professional Profile: http://tmetro.venturelogic.com/ > _______________________________________________ > Discuss mailing list > Discuss@blu.org > http://lists.blu.org/mailman/listinfo/discuss _______________________________________________ Discuss mailing list Discuss@blu.org http://lists.blu.org/mailman/listinfo/discuss