Problem of Ewf ( Disk Type )!! Please help, MS.

[Kiros]

Hi all
I have a very serious problem with EWF(Disk Type ).
I use a DOM(1.5G) and build a XPE image with EWF(Disk Type ).
After FBA and installing all applications, the free space is about
500MB.

Maximum Number of Overlay Levels = 2
EWF Partition Size in KBytes = 250MB

Default the EWF is enabled.
Everything is fine and the EWF works normally.(Restore or setlevel)
We know that the EWF partition will be wrote when you enable it.
But when the EWF partition volume had been written fully.
(Ewf Volume percent full 100.00)
The problem is coming.
It will generate a message "Write delay failed" and the system will
be crashed after reboot the XPE.(Can't boot anymore every time.)

Because the EWF partition is full and can't write anything into the
disk.
And i can't disable it because i want to use the restore function.
So i must enable the EWF when i use XPE.
I don't know what to do.
Because the EWF partition will be written when you enable it.
So it will be full one day.
Is it the limitation of EWF (Disk Type)?
Or is there anyway to slove this issue?

Thanks
Kiros

 

[Matt Kellner \(MS\)]

Hi Kiros. At boot (just after the POST screen), you can press F8 to access
a set of boot options, which should include a set of options for EWF. Here,
you can discard or commit the data in the EWF overlay and make it usable
again.

I have a few questions for you as well: Is the data you're writing to the
EWF overlay meant to be persistent? Is it application-specific data, or
does the data you want to keep also apply to the OS configuration, etc.? If
you only need to persist data for your applications, you might consider
creating a separate, unprotected partition on your device that will hold
this data, and then you can either discard the disk overlay on every
shutdown, or you can use a RAM or RAM REG overlay to make it so the overlay
is automatically discarded.

Hope this helps.

--
Matt Kellner ([email protected])
STE, Windows Embedded Group

This posting is provided "AS IS" with no warranties, and confers no rights.
===============================

 

[Kiros]

Hi Matt
Yes, the data i want to keep after reboot.
Because the data with "Ram Type" will be lost after reboot.
And i don't want to disable EWF because i can restore the factory
default if something wrong.( It doesn't mean that the system crash )

So i choice the "Disk Type".

I agree your advice about creating a separate, unprotected partition on
device to hold
the data.
But i think that the EWF partition will still be full on day.
Because all I/O procedure will be written into EWF partition.
I have try to write a simple batch file ( a.bat ) and let it run . As
below.

copy xxx.exe to xxx.111
del xxx.111
a

Even if you just do this simple job, the Ewf Volume percent will keep
increasing.
And it will be full after several hours.
We think that creating unprotected partition to hold the data will let
this issue decrease.
But it will be full one day.
Because the Ewf Volume percent keep increasing if you don't restore it.
So i don't know if it is the limitation of EWF (Disk Type)?
Or it is suitable for HD?
Or something wrong with our steps about Ewf?

Thanks
Kiros

 

[Kiros]

Hi Matt
Some system cache file will also let the Ewf partition full.
How to let Ewf partition not be wrote by these cache?
Or i must redirect them to the unprotected partition?

Thanks
Kiros

 

[Matt Kellner \(MS\)]

The behavior you described below is by design. EWF stores a record of all
write operations directed to the protected partition, and it has no innate
knowledge of specific files or operations. So if you write a 200 KB file to
the partition, then delete it and write the same 200 KB file again, you will
have consumed a little more than 400 KB of space, even though on an
unprotected partition the consumed space would be 200 KB. By its very
nature, this means that the overlay will eventually become full and start
issuing "Delayed Write Failed" messages until/unless you restore or commit
the overlay and reboot.

You can decrease this fill-up behavior by:

(a) using multiple overlay levels (EWF DISK mode only) and frequently
discarding the most recent changes, if this is appropriate to your
application,
(b) directing application-specific data to an unprotected partition so that
you can discard the overlay more frequently without losing persistent data,
(c) disabling your Page File (if you are using one) and setting up Internet
Explorer to not cache files from the Web, and
(d) increasing the size of your disk overlay.

Hope these tips help. =)

--
Matt Kellner ([email protected])
STE, Windows Embedded Group

This posting is provided "AS IS" with no warranties, and confers no rights.
===============================