Newbie EWF question

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Guest

Hi,

Can someone tell me if the following is possible?

I'd like to have a totally read-only bootable XPE partition for my device.
I'm thinking of using HORM (hibernate once read many) and EWF -- the goal is
to have a configuration where the device boots up ALL the time exactly the
same. I'm considering having this completely read-only (system) partition on
a compactflash card. Since it's solid state, it would boot up much more
quickly than IDE.

I also have a need to have a read-write partition on a mass-storage IDE disk
(for saving user data). This disk/partition would be completely separate
from the system partition, it's basically an empty partition for storing
files. It's my guess that EWF *would* protect the compactflash partition but
would *not* protect the storage partition (which also is on a completely
separate hardware disk - IDE HDD).

Now, given all of that, is it possible to have that configuration and ALSO
have the capability to remove the power at any time to turn the device off
(no shutdown - plug can be pulled at any time)? I would guess that this is
no problem for the CompactFlash system partition but could be a problem with
the user data IDE disk. I could make it a requirement that whenever a file is
written to the IDE disk, a program can be run to unmount it or whatever...
just wondering mainly what is the ramifications of "pulling the plug" where
IDE disks are present? (or any other ramifications)?

Thanks,
-Matt
 
What you are asking for can be done conceptually. The News Group has had
several requests for this setup. You control what partitions EWF protects.

CF is not faster than an IDE disk. Most CF cards don't have DMA for faster
data access, most are Port I/O mode - very slow for XPe boot. Using HORM
will speed the boot procees so you shouldn't see too much of an impact from
a CF bandwidth.

How will data be stored on the IDE hard drive? Are you going to use a
database? Regardless of the power issue, implementing HORM with storage
media can be a bit tricky to architect. There is an article that describes
how to handle data drives wtih HORM:

Dismounting Volumes in a Hibernate Once/Resume Many Configuration
http://msdn.microsoft.com/library/d...mesInHibernateOnceResumeManyConfiguration.asp

Regards,

Sean Liming
www.sjjmicro.com / www.seanliming.com
XP Embedded Book Author - XP Embedded Advanced, XP Embedded Supplemental
Toolkit.
 
Thanks for this info...

It sounds like this is doable (complexities with managing drives with HORM
and EWF aside)...

Do you have any more info on what happens if power is removed from the
device? Can data be corrupted with an EWF configuration? With CF / IDE disks
configuration?

Thanks...
-Matt
 
Data can get corrupted to the unprotected drive as data is being written.
There is a CF manufacture SiliconSystems that is offering a CF card with
some power protection.

Regards,

Sean Liming
www.sjjmicro.com / www.seanliming.com
XP Embedded Book Author - XP Embedded Advanced, XP Embedded Supplemental
Toolkit.
 
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