EWF - Commit, disable ,etc, reboot ...

[Cato Svellingen]

Hi,

I am getting confused about EWF with RAM overlay.

Is it true that both methods using EWF RAM overlay (with EWF partition and
without EWF partition), both need a reeboot of the machine in order to write
RAM overlay content to media ???

I thought that the method using fixed media CF and EWF partition, could
commit and turn on of EWF anytime ... is this wrong?

Can someone clarify please !


thanks

Cato

 

[Slobodan Brcin \(eMVP\)]

Hi Cato,

In both cases you MUST REBOOT. Simple as that :-(

I thought that the method using fixed media CF and EWF partition, could
commit and turn on of EWF anytime ... is this wrong?

Current implementation of RAM EWF does not allow disabling or enabling EWF
without reboot.
Although I have no idea why MS did not implemented commit and disable option
to work without reboot. (It is simple to do and there would no problems with
this).

Enabling RAM EWF during run time would be impossible to do safely.

Regards,
Slobodan

 

[Cato Svellingen]

OK.

Hence this means that many embedded systems that are on for long periods of
time and run CF, may have no use of RAM EWF. !?

The RAM will quickly fill up, and I guess then things may stop working ....
correct ?

Maybe it is a better option to get a Industrial grade CF that will live long
without EWF. ??


Cheers

Cato

 

[Slobodan Brcin \(eMVP\)]

Hmmm, wrong conclusion.

Our systems do not consume more than 0.5MB of RAM and they work for a very
long periods of time. (They are never off).

You need one RAM EWF protected partition (XPe OS partition). And second
partition that is not protected by EWF.
And then you should redirect all log files from both programs and OS itself
to go to this unprotected partition.

So EWF will not fill at all.

Regards,
Slobodan

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[Cato Svellingen]

Slobodan,

So If I only have one CF I cannot protect the complete CF, but at least the
OS part ...

And the second partition needs to be on the CF, or on another HDD if there
is one.

Is there an easy way of redirecting all log files to go to unprotected area
?

Thanks

Cato

 

[Slobodan Brcin \(eMVP\)]

Cato,

You do not protect whole CF, but rather whole partitions of your choice.

And the second partition needs to be on the CF, or on another HDD if there

is one.
This is not important it can be any partitions that you can write to.

Is there an easy way of redirecting all log files to go to unprotected

area?
No this will require from you to do detailed analysis. Use file monitoring
programs, etc to see what files are changed on OS partition, find programs
that change them and configure them to use other partitions.

Regards,
Slobodan

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[Heidi Linda eMVP]

Slobodan,

So If I only have one CF I cannot protect the complete CF, but at least the
OS part ...

No, you can protect the whole thing. I have systems which log data to
the protected partition, up to 128MB worth, from which it is regularly
downloaded and while I have a second partition, all that is written to
this are the application config files so that we do not have to commit -
for our application having any logged data committed would be a serious
problem.
These systems have run continually for several months under
stress-testing conditions - putting amounts of data through them far
higher than they would ever have in the field - and while we have had
crashes, they have been traced to hardware faults (loose CF cards)
rather than EWF problems. About 20 units were still happily logging away
when I left the company.