[Soekris] Industrial grade CF durability

David Goodenough david.goodenough at btconnect.com
Sun Mar 13 18:25:03 UTC 2005


On Sunday 13 March 2005 17:15, Wim Vandeputte wrote:
> On Sun, Mar 13, 2005 at 01:57:23PM +0000, Stuart Henderson wrote:
> > >Stanislav wrote:
> > >"Beware of the fact that the flashcards don't have unlimited
> > >number of write cycles and that without a special setup
> > >most filesystems do some writes even when you don't expect
> > >them to (e.g. updating a timestamp a file was last accessed)."
> > >
> > >I have done an installation on a 1gig card and it booted up perfectly in
> > >the computer (not in a soekrisbox) I tried it on. I made a /var/log
> > >partition with 300meg space and it seemed to work correctly.
> >
> > Modern flashcards are much much better than the older ones, see
> > <http://www.monkey.org/openbsd/archive/misc/0407/msg00539.html>
>
> while it's still good practice to mount certain partitions read-only
> (because it's too easy for people to forget to halt a unix machine, pulling
>  the power plug from a Soekris is very easy to do) and to put scrap
> partitions like /tmp on mfs, I have no problems in considering CF more
> reliable than a harddisk with moving parts.
>
> http://www.sandisk.com/industrial/cf-specs.asp
>
> With garantees up to 2 milion cycles it makes sense to go for industrial
> grade CF.
>
> Unfortunatly, Sandisk has announced the end of life of it's line of
> industrial grade products (still a couple of months to order them), so I'm
> now looking for an alternative.
>
> Transcend has a line of industrial CompactFlash cards, but it's hard
> to compare the marketing lingo with that of Sandisk.
>
> For example,
>
> http://www.transcendusa.com/products/ModDetail.asp?ModNo=15&SpNo=3&LangNo=0
>
> mentions Durability : >100,000 program/erase cycles
>
> Comparing the Consumer Grade and Industrial grade Transcend, the following
> differences stand out:
>
> 0. wider temperature range (0 to 70 versus -40 to 85 degrees Celcius)
> 1. ECC: 1 bit
> 2. higher shock resistance
>
> The only thing relevant to 'our' application here is point 1. but I have
> no clue how to compare the durability...
>
> Does anybody have experience with alternatives than Sandisk Industrial
> Grade?
Pretec seem to make some industrial grade CF cards.  They are readily 
available in the UK, but I do not know about other markets.  I have had
one which was dead-on-arrival, but the others have worked very well.  I
have used both normal and industrial ones with no obvious differences,
but I have not done any formal experiments.  These were not on Soekris
cards, but rather Microtik and PC Engines.

David
>
> Wim.
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