> another is the write speed, flash is relativly slow to write to, I would
> not expect it to have nearly the performance of battery-backed ram.

Be careful with broad statements without qualification. All flash is not 
created equal.. Far from it.
The Intel X-25 series are blazing fast for writes, as are the OCZ. They 
do this by putting a bit of RAM in front of the flash and a 
super-capacitor on the entire assembly for when the power goes out. You 
can get about 100X-1000X the IOPS of disk this way. The new thing coming 
out is this thing called E-MLC, which is an enterprise multi-level chip. 
It is supposed to get the same 1,000,000 hours of usage as the SLC 
without minimal write degradation (usually on operations where you are 
writing to the same block or neighboring blocks of flash repeatedly).

These are not the consumer grade flash drives that plug into USB that 
are slow on writes.

I read a great benchmark recently comparing the OCZ Vertex vs the Intel 
X-25 where the OCZ came out on top, but I can't find it right now. It's 
not this one: 
http://www.guruht.com/2010/01/ocz-vertex-2-ssd-pro-sandforce-vs-intel.html 
(which is interesting and useful, but not the one that I was looking for.

Also keep an eye on Pliant. They are very expensive, but large capacity, 
and generally the new shiny, delivering SAS enterprise flash instead of 
SATA like everybody else. Once this catches on (prices drop) we may see 
the shift to SAS based storage for high availability clustering 
accelerate since SATA is so poor at that.



.


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