I am not sure how you tell. The disks I have been working with were
ordered thru a board vendor & were supposed to be validated somehow for
their product. They look different from what is available in stores,
since they have a large black bar code on the back and a date 5/15/02. A
disk I recently picked up at CompUSA had a different color scheme and
only had markings on the edge of the card.
This new disk has been working for more than a month in the app, but has
not been subjected to repeated power outages. When I emailed SanDisk
about possible quality differences between these disks, they said they
had changed the marking scheme, and made no mention of availability of
different grades. They gave me the impression that newer stock would be
of better quality than something purchased a year ago.
If the FS has no control or knowledge of wear-leveling, what advantage
do you think ext3 will provide as opposed to JFFS2? If the CF contains a
dedicated controller, it makes sense for it to implement a powerfail
scheme of its own, although a system level solution (UPS, supercap)
rather than a 'media level' solution would seem more promising.
> From what I've read I believe JFFS2 is not adequate for CF, since most
> CF cards do internal wear levelling. Read prior posts to this group for
> Are you using industrial Sandisk or consumer grade ? I've always
> wondered if industrial is better. I also have some of the same problems
> you have, and I'm about to try industrial grade. As for ext3, I'm also
> going to try it.
>> Good questions.
>> I have an embedded app using a 2.4.18 kernal and slimmed down ext2 RFS
>> on a 64MB SanDisk. During development I had cycled power dozens of
>> times on the system without any obvious file corruption - it always
>> booted and ran at least. When I finally read about ext3 and JFFS2, I
>> realized that just flipping the power switch on ext2 was probably a
>> bad idea. I ran e2fsck and it found lots to fix, but nothing it could
>> not handle. Whatever SanDisk is doing inside the card it can't be too
>> bad, but my app does very little file IO.
>> Recently one of the flash cards on a duplicate system (with the same
>> power off methodology) failed to boot, but could be reformatted
>> without any obvious damage or loss of storage (it could have taken out
>> some extra blocks without me knowing I suppose).
>> More questions:
>> When faced with unknown wear leveling, does ext3 or JFFS2 add any
>> value in a CF configuration?
>> Has anyone implemented the 'hang a big cap off the flash' solution?
>> If you are designing from scratch this may work, but probably not as a
>> retrofit for existing boards.