On Tue, 7 Aug 2012, Sašo Kiselkov wrote:
MLC is so much cheaper that you can simply slap on twice as much and use
the rest for ECC, mirroring or simply overprovisioning sectors. The
common practice to extending the lifecycle of MLC is by "short-stroking"
it, i.e. using only a fraction of the capacity. E.g. a 40GB MLC unit
with 5-10k cycles per cell can be turned into a 4GB unit (with the
controller providing wear leveling) with effectively 50-100k cycles
(that's SLC land) for about a hundred bucks. Also, since I'm mirroring
it already with ZFS checksums to provide integrity checking, your
argument simply doesn't hold up.
Remember he also said that the current product is based principally on
an FPGA. This FPGA must be interfacing directly with the Flash device
so it would need to be substantially redesigned to deal with MLC Flash
(probably at least an order of magnitude more complex), or else a
microcontroller would need to be added to the design, and firmware
would handle the substantial complexities. If the Flash device writes
slower, then the power has to stay up longer. If the Flash device
reads slower, then it takes longer for the "drive" to come back on
line.
Quite a lot of product would need to be sold in order to pay for both
re-engineering and the cost of running a business.
Regardless, continual product re-development is necessary or else it
will surely die.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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