For what it's worth, the system was called "Jackdaw" and was written by 
Mike Challis.  It was in extensive use on the University's MVT/MVS/MVSXA 
mainframe for many years as the database for holding user information.  The 
document Alain's got is probably Computer Laboratory Technical Report no. 1 
(yes, One!).

If it isn't, and you need it, see

     http://www.ftp.cl.cam.ac.uk/ftp/papers/reports/TR.txt

Jackdaw was phased out when the mainframe was decommissioned about 5 years 
ago. Mike's still around, but I think he's retired.

  -- Timothy


At 10:00 PM 10/5/00 +0000, Alain Williams wrote:
>Hi,
>
>I remember when at the University of Cambridge (in England) about 25 years ago
>seeing some work then about the Jackdaw (or was is Jackard) database system
>that had the great feature of being immune to OS crashes, it used a phased
>update mechanism where new blocks were written to disk and the last block
>written was the one that contained the switched pointer, until this last block
>had been written the changes had not been made. Since the write of a disk 
>block
>was atomic the database would never be corrupt.
>
>If someone wants I think that I still have a (paper) copy of the report 
>describing
>this. I can send/fax a copy if wanted.
>
>I don't subscribe to this list, so please reply direct if someone wants it.
>
>(Please don't request a copy just out of curiosity since I don't want to have
>to post/fax copies that won't help resolve this case by showing prior art.)
>
>Cheers
>
>--
>Alain Williams
>-
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