cvs commit: src/sbin/atacontrol atacontrol.c

[Poul-Henning Kamp]

In message <20071217.091901.627251640.imp at bsdimp.com>, "M. Warner Losh" writes:
>In message: <11419.1197903331 at critter.freebsd.dk>
>            "Poul-Henning Kamp" <phk at phk.freebsd.dk> writes:
>: > * NAND Flash devices should not have their sectors erased unless 
>: >absolutely necessary, to implement wear levelling.
>: 
>: Wrong, almost exactly the opposite in fact:
>: 
>: Flash devices using wear-levelling should have data erased as soon as
>: possible to give the wear-levelling the maximum amount of information
>: and available space to work with.
>
>The formula for flash life has two components: The percentage of space
>available and the data rate.  So the more space, the longer it will
>last for a given rate.

It is actually quite a bit more complex than that, but for people who
don't have access to the actual FAL algorithm, it is a useful first
approximation.  For some of the non-patented, practically unused
FAL algorithms, it is even the strict truth.

For NDA reasons, I can't go into too much details, there is a couple
of very read-worth patents which M-Systems got and SanDisk bought
with the company, which they are now sueing everybody and their
aunt for infringing.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.