Why use EWF on Compact Flash cards?

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brendan

Hello All,

I have an application written for XP Pro that is an HMI for industrial
controls. I've rebuilt it for XPE and it works fine.
My supplier questions why use XPE instead of Pro. I explain that I want
solid state memory (no moving parts) therefore I want it small etc.
He says that CTC-Parker has sold many Industrial PCs running XP Pro on
4 Gig Flash cards and have no issues with Memory failure (and have data
to back them up) If they are running XP Pro on compact flash why am I
even worrying about EWF?

Am I missing something here?

I have my application come up in a shell I'mguessing I could do
something similiar in XPP??....
What am I really gaining with XPE? [ Am I being sacrilegious? ; ) ]

BK
 
brendan said:
Hello All,

I have an application written for XP Pro that is an HMI for industrial
controls. I've rebuilt it for XPE and it works fine.
My supplier questions why use XPE instead of Pro. I explain that I want
solid state memory (no moving parts) therefore I want it small etc.
He says that CTC-Parker has sold many Industrial PCs running XP Pro on
4 Gig Flash cards and have no issues with Memory failure (and have data
to back them up) If they are running XP Pro on compact flash why am I
even worrying about EWF?

Am I missing something here?

I have my application come up in a shell I'mguessing I could do
something similiar in XPP??....
What am I really gaining with XPE? [ Am I being sacrilegious? ; ) ]

BK
Click to expand...
....aside from the unit price being considerably lower and that EWF can
help prevent user screwups as well as disk issues? Personally I wouldn't
go near something with XPPro on CF.
 
Compact flash cards have a limited number of read/writes before the
card will actually fail. This is true of consumer and industrial grade
compact flashes (although industrial CF lasts longer). The purpose of
using an EWF is to protect the compact flash from excessive use by
offloading it to memory or a hard drive. This extends the life of the
flash card greatly.

As for running the full XP Professional on a 4GB flash....I would be
concerned with the cost of an industrial grade compact flash and the
life span since no EWF is being used. Seems like a poor solution to me.

gasmonso
 
If you want a stable system I recommend to enable EWF on CF.

We have several applications with XPe on CF without EWF (page file support
disabled). This configuration we use since two years with success. Before we
used harddisks we had a lot of failures which occured of vibrations. With CF
we could eliminate this problem. With XPe and its limited running services we
have also got the advantage, that we do not need that calculating power which
XP Professional needs. So we could choose hardware without any rotating parts.

An other division of our company uses XP professional on CF. At the moment
they have the problem, that CF must be changed every half year. I assume, it
is the limited writing cycle problem. So they must change to XPe without page
file support.

For a future application we have developed an enabled EWF configuration. We
need EWF because this application must be power loss proof.

This are the facts, why we have choosen to install generally XPe with CF on
our target systems in future.

best regards,
Peter
 
Peter said:
For a future application we have developed an enabled EWF configuration. We
need EWF because this application must be power loss proof.
Click to expand...

I want to subscribe to this point specially. Beside of the limited
numbers of write cycles on a flash medium power loss proof is really a
point. We learned that in 1 of about 200 cases of taking power without
shutting down a file system error (ntfs) occurs. Mostly file system
consistency is regained by the journalling capabilities but sometimes
data loss may happen on boot important files. So your system is really
crashed.

Beside, using a very large disk with much free space on it supports life
time in an ewf-less system because write cycles are distributed
intelligently by the compact flash disk's controller over all flash cells.
 
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