[Info-ingres] 4k Cache

[Roy Hann]

Steve wrote:

> Recently the 4k DMF cache was enabled across our Ingres environments.
> 
> I notice in CBF, for our production environment, the cache type is
> "shared"  vs in our development environment, where the cache type is
> "private ( owner=(default) )." The respective lines from the production
> and development configuration files are shown below:
> 
> Production config.dat: 
> ii.<server>.dbms.private.*.cache.p4k_status: OFF 
> ii.<server>.dbms.shared.cach_def.cache.p4k_status: ON
> 
> Development config.dat: 
> ii.<myserver>.dbms.private.*.cache.p4k_status: ON
> 
> Is the difference due to the fact that production has four DBMS servers
> vs the single server in development?

Yep.

In principle an iidbms server process can serve all your databases. If
you have more than one server process they need to have a coherent view
of the cached data, so they need to share the cache.

Back in the steam age it was claimed--though I doubt it was ever
experienced by any human user--that having a private cache eliminated
the need to negotiate for access. Being private was claimed to give a
performance benefit. (Personally I never saw a system where that would
have been anywhere near the top of the list of performance drags.

Roy