[OT] MRAM, spintronics, the future

Marcus Denker marcus at ira.uka.de
Wed Feb 12 09:07:50 UTC 2003

On Tue, Feb 11, 2003 at 05:29:25PM +0100, goran.hultgren at bluefish.se wrote:
> Save a document? Start a program? Reboot? A filesystem? ...why? :-) All
> programs can be kept running all the time etc. A document can simply
> "stay" in memory. Why change representation into a bucket of bits?

Yes, MRAM is interesting. But: The things you want can be done today.
You don't need static memory to do a persistent object store: Just
add enough batery-power to allow saving the contents of the ram on the
disk in case of power-failure. 

There are some nice papers about the Rio File Cache:

The Rio File Cache: Surviving Operating System Crashes

The interesting thing they found out is 
a) operating system failurs do not corrupt application memory very
b) Ram-contents survive a warm reboot 

===> The rio file cache (memory only) is nearly as reliable as a disk.

"These results stand in sharp contrast to the general feeling among
computer scientists". 

They used RIO for building a *very* fast transaction system:

Free Transactions with Rio Vista

and discount checking (persistent execution state for normal 
C programms):

Discount Checking: Transparent, Low-Overhead Recovery for General


Marcus Denker marcus at ira.uka.de  -- Squeak! http://squeak.de

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