RE: data corruption

[Tom Droege <tdroege@veriomail.com>]

I come from the Seymore Cray school of designers.  "Parity is for 
Amateurs".   Hmmmm!  I guess we claim to be amateurs.  Still, a checksum 
will tell you that data that you already know is bad is bad.  Not much 
worth the effort, I think.  OK, a checksum would detect one missing bit 
somewhere that would not otherwise be detected.  Most of our data is 
noise.  A missing bit here and there is not a disaster as it would be if we 
were transferring billions between banks.  There are a lot of other things 
much higher on my list. At the moment it is tracking down whole images of 
bad data, fixing cameras, finding a spot to put Rob's program so that it 
does not use any time, etc..

Note this all comes from me sending out a lot of bad data because I used 
the minimal time process to copy disks.  If I had done read after write 
testing, they would still not be out.  As it is, most of you have 9 out of 
10 good disks and much good on the tenth.  Good enough for this preliminary 
work, I think.  Later I can send out replacement copies of disk 18e.   I am 
waiting for someone to send me a curve of a new variable that would benefit 
from one more measurement.  ;^)

Tom Droege

At 11:46 AM 6/8/01 -0600, you wrote:

>Chris (and all),
>
>I just looked at CFITSIO, and indeed, there is a group of routines for
>creating/checking checksums.  I can easily add these in (provided they work
>with the windows version) if desired.  There would be two new keywords
>added, DATASUM and CHECKSUM, with associated ASCII string of quoted digits.
>
>Let me know.
>
>Cheers,
>Rob