Kevin said:
>
> Maybe this is my CF-ignorance but stompbox appears to use a CF card like
> my
> digital camera uses. Take a look at this page:
> http://www.stompboxnetworks.com/cfimg.html
>
> Since my camera does a lot of reading/writing over the course of years,
> maybe this would be sufficient. Just guessing.
I don't have time to go into detail right now. I'll give you some bullet
points about flash wear out. You can ask for more if you want it.
- Flash storage is evolving rapidly with everything from the silicon up to
the CF controller getting better and better.
- Having said that, there is wide differences between manufacturers and
product types. For examples:
-- Most consumer flash uses "multi-level cell" flash chips because they
are higher density for less cost. They are also less reliable and wear
out faster.
-- It is correct that most USB flash drives have the least amount of wear
out protection.
-- There are many other factors to this, these are just two points.
- Cameras, music players and other consumer devices use flash in a best
case scenerio manner. They write and read mult-megabytes at a time.
- Computer OSes, Linux included, tend to write and read small amounts of
data at a time. For example, a normal cluster size for a filesystem is
4k.
For various reasons all the way down to the silicon in the flash chips,
this is a worst case scenerio for flash wear out.
- The controller in the CF module employs things like wear-leveling and
spare blocks to make the usable capacity last longer.
So, while I'd expect a CF card to last longer than just a month or so, a
default Linux install on a consumer CF card will probably crash the card
within a year. Generously speaking.
If you can get "industrial" CF cards from a top tier supplier (SimpleTech,
SanDisk, Samsung, Toshiba), for a lot more $$, it should do very well for
much more than that. Especially if the OS and applications are configured
to write to the media as little as possible. Adtron's standard warrenty
for our flash media drives is 3 years which gives you some idea what good
flash can do.
If you use consumer flash, buy 4 or 5. Once you have the master
configured, image it onto the extras. Then, when the first one dies you
can just plug in the next one ready to go. That can still be cheaper than
paying for industrial grade CF cards and you still have a solid state and
silent media.
> I have seen some "micro-drives" that have a CF interface. That might get
> me
> around the media problem. I need to do more research on those. I think I
> will start here:
> http://en.wikipedia.org/wiki/Microdrive
Microdrives work well and tend to be much cheaper than flash although not
a durable. Most of the music players on the market use micro or very
small hard drives so they are pretty good to. Since you will not be
moving these firewall boxes around, they may be the right solution for
you.
Alan
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