On 6/3/2012 10:55 PM, Tom Metro wrote:
So more silicon...
Less, actually. Enterprise-class SSD vendors cheat.
Say that Toshiba makes a 128G MLC flash chip (which they do, in fact).
This chip sold as part of a SandForce consumer device would have the
controller set at 120G storage capacity. The difference between binary
and decimal calculations is used to over-provision the drive by the
typical ~7.5% found on consumer SSDs.
An enterprise-class vendor like STEC would take that chip, put it on
their own proprietary controller, and set the capacity at 64G. Instant
100% over-provisioning. And then they would sell it for ten times the
price of the SandForce unit because STEC's SSD would last five years
where the SandForce unit would burn out in 6 months.
A vendor like Violin or EMC would take 16 or 32 of these 128G chips, set
their capacity at 64G, and glom them together on a tray for a storage
frame. It isn't "more silicon" in the form of larger flash chips; it's
"more silicon" in the form of more flash chips.
All with the same "consumer-grade" flash chips.
That's not to say that all of these chips are equal. They're not.
You'll get a better product from Toshiba than you will from Adata.
Of note: consumer SSD makers cheat the same way but they're generally
more open about doing so. It's easy to figure how much
over-provisioning you have on a 400GB SSD when the controller has
sixteen 32GB flash chips on it.
--
Rich P.
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