--- In os2hardware{at}yahoogroups.com, "Lloyd Fuller"
 wrote:
>
> On Sun, 30 Sep 2007 07:22:29 +1000, Mike O'Connor wrote:
> 
[cut]
> 
> There is no such thing as a free lunch.  What the articles,
including the ./ article, fail to mention is the number of write 
> cycles on flash memory.  You can only do a limited number of writes
to flash memory, and then you no longer have 
> flash memory.  Admittedly, that number is in the hundreds of
thousand range, but it is still significantly less than the 
> average life of a hard drive.
> 
> For installing products including operating systems AS LONG AS you
keep temporary files including swap off of it, it 
> will probably be great.  But do not put your Firefox temp directory
or your swap file on one or you will not have it 
> quickly.
> 
> Lloyd
>
It is better to wait for a solid state drive based on phase-change
memory http://en.wikipedia.org/wiki/Phase-change_memory>.


With Flash, each burst of voltage across the cell causes degradation,
so most flash devices are only rated for something on the order of 10
000 to 100 000 writes per sector, and many flash controllers perform
wear levelling to spread writes across many physical sectors. As the
size of the cells decrease, damage from programming grows worse
because the voltage necessary to program the device does not scale
with the lithography. This accounts for the shortened life-expectancy
of many popular flash-based portable music devices.[citation needed]

PRAM devices degrade with use, for different reasons than Flash. A
PRAM device may endure around 100 million write cycles [1]. PRAM
lifetime is limited by mechanisms such as degradation due to GST
thermal expansion during programming, metal (and other material)
migration, and other mechanisms still unknown.


Daniel




 
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