Protecting fixed CF with disk resident EWF overlay

[Guest]

XPe SP2: We would like to boot a fixed IDE flash drive and deploy the EWF
overlays to a separate hard drive. This would permit overlay stacking with
flash media and allow selective layered updates to the more reliable flash
drive as required.

None of the help screens place the EWF partition on nonboot media. All
three modes (disk mode, ram mode, ram + Reg) all place the EWF overlay on
the boot media or system RAM.

Is there a way to locate overlays on nonboot media? Observations would be
most welcome. Thanks!

 

[Sean Liming \(eMVP\)]

Nonboot media as flash or ROM? OR a second non-bootable hard drive?

If a second non-bootable hard drive, the answer is yes. The EWF volume can
be placed on a second hard drive so longs as there is one partition already
on the drive.

Are you using Disk Overlay?

Regards,

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

 

[jimt]

The nonboot media would be a second unbooted hard drive, D:, partitioned to
support a EWF partition. The booted "C:" drive would be the IDE flash
drive. Yes, we would use disk overlays of C: and the disk overlays would
be located on the unbooted HD at D:.

Unless I'm missing something, all the procedures in the documentation places
the disk overlay on the booted media. What procedures would place the EWF
volume and the overlays onto the unbooted spare HD? Would we need to
disable the FBA creation of the EWF volume, and create the EWF partition by
hand somehow?

Thanks very much for any tips...

 

[Sean Liming \(eMVP\)]

Do you have Windows XP Embedded Advanced?

Chapter 10 discusses the EWF specs, and Chapter 19 discusses the secenario
that you are looking for. The setup is that the IDE flash is completely
allocated and is the primary disk. The hard drive has a non-bootable
partition with unalocated space large enough for the EWF volume with Disk
overlay. As the EWF volume gets created, the FBAdll.dll will look for the
first free unalocated space following a partition, in this case the space on
the hard drive.

Regards,

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

 

[jimt]

Yes, I have the book. I found the section you mention (19.3.5 - Scenario
4). I confess I had not got that far into the book yet. This does cover
the case I asked about.

In Scenario 4 there are two fixed media... the booted CF and the spare IDE
hard drive. How does EWF know to use the hard drive for the EWF partition?
I see that the XPe boot image on the CF is configured to use disk overlay,
Does EWF search the CF for space after the first partition, find none, and
then go on to find space on the HD and use it for the EWF partition?

Bye,

jimt

 

[Sean Liming \(eMVP\)]

The ewfdll.dll starts with disk0, disk1, disk2,.... looking for empty space to create an EWF partition. If there is a partition followed by unpartition space big enough to hold the EWF parition, than ewfdll.dll will create one. If a drive does have any partitions, ewfdll.dll will fail to create one, and revert to RAM-REG. This is a trick I found experimenting when writing the first book.

Regards,

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

 

[jimt]

Yup, that explains it. No mention of this in the XP Studio help screens. Good thing we have your books and this news group.

Thanks!

--
JimT

The ewfdll.dll starts with disk0, disk1, disk2,.... looking for empty space to create an EWF partition. If there is a partition followed by unpartition space big enough to hold the EWF parition, than ewfdll.dll will create one. If a drive does have any partitions, ewfdll.dll will fail to create one, and revert to RAM-REG. This is a trick I found experimenting when writing the first book.

Regards,

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

 

[Sean Liming \(eMVP\)]

It was a painfull experience to figure it out. Once I wrote the EWF chapter, I thought I was done with EWF, until I ran into CF and EWF. What was a planed for a few hours, took a week.

Good luck.

Regards,

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




Yup, that explains it. No mention of this in the XP Studio help screens. Good thing we have your books and this news group.

Thanks!

--
JimT

The ewfdll.dll starts with disk0, disk1, disk2,.... looking for empty space to create an EWF partition. If there is a partition followed by unpartition space big enough to hold the EWF parition, than ewfdll.dll will create one. If a drive does have any partitions, ewfdll.dll will fail to create one, and revert to RAM-REG. This is a trick I found experimenting when writing the first book.

Regards,

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

 

[jimt]

Hi Sean,

I found on later review that the XPe Studio TD help says that locating an
EWF volume on a different drive than the drive containing the protected
volume is not supported. On the XPe SP2 TD Help page entitled "EWF Disk
Mode" I see this:

"EWF Disk mode requires unpartitioned space on the same disk that
contains the protected volume. The EWF volume and Overlay, collectively
referred to as the EWF Partition, cannot be created on a separate disk or on
a raw, unpartitioned disk."

Sean, I think this means it might work, based on your experiments mentioned
in Chapter 10, but apparently it is not supported by Microsoft. Is it
really safe to do?

I would be curious to hear your thoughts, in light of this quote. Thanks,

 

[Sean Liming \(eMVP\)]

It worked in SP1 and I thought I double checked this in SP2, but it has been
awhile. It is not going to hurt anything to give it a try. You will have to
have at least one partition on the second for the EWF volume to be created.

Regards,

Sean