Subject RE: [IB-Architect] Disk data integrity (was: Torn Page detection)
Author Claudio Valderrama C.
> -----Original Message-----
> From: Charlie Caro [mailto:ccaro@...]
> Sent: MiƩrcoles 8 de Noviembre de 2000 13:25
> I guess I qualify as "other than Ann". The current engine doesn't do
> anything to ensure disk data integrity except for a 'weak' page type
> check on each fetch of a page. There's database shadowing and RAID
> mirroring but that doesn't help if the page is corrupted in memory and
> then rewritten to disk.

For what I understand, the engine only ensures the TIP is written after the
page itself has been written (so there may be orphan pages but not dangling
references to non-extant pages).
However, given enough file system's cache in the OS, this may not suffice
as the cache may not be easily flushed after each write operation. Also, the
mechanism doesn't protect against records than span two or more pages.
Probably a db page that spans more than one file system cluster is already
a consistency problem.
Corrections welcome, of course.