On 18 Nov 07, at 0614, Dennis Peterson wrote:
>
> Have you considered scannning only files that have changed (md5sum  
> difference, for
> example) since the last time they were scanned? There's no need to  
> scan a file
> endlessly - only if it has changed since the previous scan.

Hmm.  Firstly, computing an MD5 sum of a file is just as much I/O,  
and probably as much CPU, as just scanning it anyway.  And secondly,  
if there has been a pattern update since the previous scan it's  
possible that the file will now be positive, even if it was negative  
when first scanned.  If you trust the mtime/atime/ctime triplet (if,  
say, the storage is coming off an NFS applicance that you're  
comfortable isn't prone to infection) then I suppose you could do  
something with looking at those and only scanning if those haven't  
changed and the file is older than some ``anything bad will have been  
spotted by now'' horizon.

ian

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