Steen,

In addition to ensuring that the disk write completed properly, the
checksum has other advantages/uses - ensures that no data has been
changed by an "outside" process, whether accidentally (hard disk errors)
or deliberately (admittedly this is a very crude method which could be
easily overcome by a 15year old)

Your posting does raise a very interesting question.

Can someone (preferably, other than Ann - she has enough to do) explain
how the current engine ensures disk data integrity.

Of particular interest is the way that writes of large size pages (16kb,
when the sector size is 512b), as well as updating single rows which
span multiple DB pages.


Sean
-----Original Message-----
From: jansdal@... [mailto:jansdal@...]
Sent: Wednesday, November 08, 2000 7:16 AM
To: IB-Architect@egroups.com
Subject: Re: [IB-Architect] Next ODS change (was: System table
change)


Ann,

Instead of calculating page checksums, I will suggest
that you implement a very fast "torn page detection"
algorithm.

The SQL Server 7 has this optional torn page detection feature:

<snip>