EWF-RAM protected partition on Compact Flash becomes unbootable

B

Billw

Hello,

I have been running a small (115MB) XPe(SP1) build for 5 years
on a SimpleTech 256MB CF that reports itself as a fixed drive.
Over these 5 years I have gone from a rock solid startup to an
increasingly suspect boot process. My users are experiencing
more non-recoverable BSOD at bootup including Registry File
failures. The only fix at this point is to overnight them a
new customized Compact Flash.

I am protecting the C: partition with a RAM based EWF and I have
left the D: partition unprotected and available for the main
application, data files associated with the application and an
application error log file. A third area on the CF has been
allocated for the EWF. The only way to powerdown this embedded
system is to 'slam' the power off!

1st goal...return to that robust system I once had that can
reliably survive shutdowns. How is my EWF protected partition
getting compromised? Is this a problem with my CF? I have been
using the same CF, although its internal controller has changed 3
times! On occasion, important directories on the unprotected D:
partition get trashed. When I attempt to browse to them, the OS
asks me if I would like to format the disk.

2nd goal...when an OS failure occurs what is the quickest way to get
my customer up and running? Can I switch to a larger CF and create a
dual boot system on the CF and switch to the 'copy'?
 
S

Sean Liming \(MVP\)

1. Are you using FAT32 or NTFS on the CF drive?
2. If data is being writen to the second partition when the system shutdown,
it is very possible that data could get corrupted.
3. Also, the CF card changes could be a problem, you might want to test
another manufacturer.



Regards,

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

Billw

Thank you for response Sean

I am using FAT16.

It is possible but not likely that the application will be writing during a
shutdown.
If a shutdown was happening during a write operation are all the directories
on D: vulnerable to some kind of corruption? My log files have their own
directory seperate from the main application...yet it seems the application
folder is the only folder that becomes unreadable.

Several years after this embedded system was in the field, I noticed that
the write cache property for the compact flash was enabled. This is not the
state I would have knowingly chosen but with several years of successfull
operation in the field I was reluctant to change. Do I need to reconsider
this setting?

I am in the process now of evaluating an industrial strength CF from
Sandisk. It will be difficult to tell in the short term if changing to this
CF is a positive or negative step. I know when I changed to the SimpleTech
card I noticed a dramatic increase in the number of FBA's the card would
tolerate. In fact, I have never been able to kill a SimpleTech card with
FBA's!

Billw
 
C

crus

Hello Billw,
if users get accustomed to power off the device and this happens when the
data are copied from the cache to the CF,
there are chances that files becomes corrupted. Perhaps years ago users were
not so confident
and so careful to shut down before powering off, so data had time to be
recorded...
If your system writes continuosly data to the CF have you checked that the
maximum number of write cicles has
not been reached? The symptoms are the same.
I haven't experience with SimpleTech, since I use DFI AC46 Industrial Grade
Fixed to do FBA during development
so I did it on each memory a lot of times without any failure ( until now!).
Regards Raffaele
 
B

Billw

Thanks again

The write caching that I am referring to is:
Device Manager>Disk Drives>STI Flash 8.0.0>Properties>Policies
It is at this point that I see that 'Enable write caching on the disk'
is checked.
This seems to be a dangerous setting!

Can the corruption of the directories on D: have an effect on EWF-RAM
protected C:?

Billw
 

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