You're still being really vague on your requirements.  Sometimes you talk 
about a filesystem that can't be modified after it has been written, and 
other times you talk about a filesystem that can be updated, but only to 
add information.  Sometimes you talk about a read-only restriction that is 
effective against the superuser (not possible) and other times say that 
it's OK if the superuser can modify the filesystem without a trace.

In addition to new ext3 features, using isofs, and chattr, mounting 
read-only and using file permissions also effect read-only status, and 
you'd have to explain how any of these don't meet your requirements.  But 
rest assured that none of them is effective against the superuser.

quoted text
>Upon changes to its content (via dd) it will invalidate the immediate 
>future incremental checksum.

I couldn't tell what "it" is in this sentence, or what checksums you're 
thinking of.

--
Bryan Henderson                     IBM Almaden Research Center
San Jose CA                         Filesystems

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