Compact flash issues

[riccardo.tonon]

Hi,

I''ve installed XPe on a compact flash Industrial grade (1 GB).
You could think: wow, a newbie! Can it search a little more?

It's not the case.

I needed something that let me store data. So I started to think that
EWF is not the "SOLUTION" for my case.

I proceded in this way:

partitioned the CF in 2
C: (where XPe and programs stand) - 700 MB with EWF
D: (where I store data) - 300 MB

To make this I bought an Industrial grade CF from Apacer.

After 2 month I got error with the filesystem that couldn't delete or
rename some files on the D: partition. (THe one with EWF disabled ).

Does anyone think that it could be a disk failure problem due to the
"unprotected" partition?

Googling for max read/write cycles on a CF I found very different
answer to the same question.

There are 2 types of CF:
Standard
Industrial Grade

Now.
The system should write a quite big amount of files, just think about
a browser sessions folder.

Why the Industrila grade CF failed?
How can I check it?

What is approximatively the real max read/write cycles number for an
industrial grade?
Does anyone use an industrial one for an application?

Please,
Help me.

Riccardo

 

[Richard]

Normally - the industrial has:
1,000,000 write cycles
Extended Temperature
* some have wear leveling

Retail
* most use to have only 100,000 write cycles but some are up to the
1,000,000 now
Normally does not have wear leveling
Standard Temp. Range.
Possibly a lower level of QC checks?

We ran a test in the field, with Sandisk Industrial on numrous units, and
then various retial versions of CF. They were running identical images with
Ram Reg EWF. Within 90 days, most all of the retial versions failed.
Another company I work closely with decided they would save some money.
They run embedded Nix. They were using Industrial SanDisk until SanDisk got
out of the Industrial market. They started using "off the shelf" retail
versions of CF. Withing the first year, their failure rate exceeded over
60%.Some will reformat fine while others are no longer usable at all. That
seemed to be about a 50/50 split.

We have seen only a couple of failures on our Industrial CF out of 300
systems running, Most have been in the field for two or three years running
24/7. Both reformatted fine. Both had corrupt NTLDR files. How with EWF?
The only things I could possible think of is one lost power during a commit
since someone was on location doing a configuration change, the other failed
to boot after a severe lightening storm.

Richard

 

[lino]

Hi Rchard,

why in your test retail Sundisk CF failed if EWF was used?
I have a similar problem listen in this forum ... thank for details.

Paolo

 

[Richard]

On the couple we lost, the only thing we could think of if there was an
interruption during a commit and restart cycle. I have no idea why we lost
the other in a storm unless a static discharge affect the compact flash.

The other company I was referring to run Linux with out any type of write
filter. The use MySql pretty heavily to store data from logging. Since
they did not seem to have issues using industrial versions it would be hard
to say it but it could be the Ind version was using a fail safe file system
like some have so corruption during power downs were reduced, or they
exceeded the write limitations on the flash.

What's bad is they just keep replacing flash drives instead of resolving the
issue. After many trips to the field to replace their flash we finally quit
using their devices and used our own.

Richard

 

[Sean Liming \(eMVP\)]

To the original poster - you might want to look at FBWF and open holes for
the data to be writen directly to the drive. Might be better than splitting
partitions since CF controlers want to do block moves and you have two
partitions the controller is trying to maintain.

EWF doesn't necessarily protect the whole driver. Under NTFS, the meta data
portion is not protected, and for FAT and NTFS there is a vuneralbility
before the driver is loaded and when it is unloaded.

Not all CF cards are the same. I would look at the WinSystems CF -
http://www.winsystems.com/products/misc/wincflash.html. They seem to have a
better consistancy with their product line.

Regards,

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

 

[lino]

Hi Sean,

so my problem listen in this forum as 'CompactFlash corruption and EWF'
(first post on 11-5-07) may be due to this. I saw messages related to
writing errors on D:\$Mtf. Is FBWF better than EWF? Are multi partition
fully supported on CF devices? I didn't find documentation at all related to
this EWF limitation.

Regards,

Paolo

 

[Sean Liming \(MVP\)]

1. The issue of writing to the metadata sections would be the same for FBWF.
2. Under XP /XPe, these OSes can only see one partition on a dived IDed as
removable. If the CF was fixed then you can perform multipartitions - The CF
cards from WinSystems http://www.winsystems.com/products/misc/wincflash.html
are IDed as fixed.

--
Regards,

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

 

[riccardo.tonon]

Dear Sean,

Thank you for your support.

I forgot to post that:
my first partition (where XPe runs) is NTFS
the second one is FAT

Does it generate some issues?

I'm using an industrial grade CF IDed as fixed.

Which FS is the safest?

Riccardo