Re: FFS Panic with CF Card

[Andy Isaacson <adi@hexapodia.org>]

On Wed, Jun 12, 2002 at 07:28:39PM +0200, Harald Schmalzbauer wrote:
> I'm about to do a Soekris router. I bought a CF-IDE adaptor which simulates
> a ZIP-100, so I can Hot-Plug the CF.
> OpenBSD (3.1) recognizes this adaptor as "atapiscsi" and I can access the CF
> as sd0. But I always get the following error:
> 
> sd0(atapiscsi1:0:0): Check Condition on opcode 0x5a
>     SENSE KEY: Illegal Request
>     ASC/ASCQ: Illegal Field in CDB
> 
> And when I try to copy lots of files the whole system panics.
> 
> panic: ffs_clusteralloc: map mismatch

I can't address the specific issue you're having, but you should be
aware that Flash memory has a physical limit on the number of write
cycles it can support.  The Berkeley Fast File System is not designed
with this kind of limit in mind, so I would not recommend it for
writable flash-based applications -- you may well find that the system
is re-writing the blocks-in-use bitmap 100 times a minute, and your
flash card will become useless in a day or two.

Digital cameras use the FAT filesystem, and I believe they are generally
careful not to overwrite a single sector frequently.

You will be OK if you just write the filesystem to the card once, and
then mount it read-only.  I would not recommend EVER mounting a FFS
filesystem read-write on a Flash medium unless you've analyzed the
situation above.

-andy