--- In firebird-support@yahoogroups.com, "mohamed.banaouas"
<mohamed.banaouas@...> wrote:

>
> thanks a lot for your feedback.
> On SuperServer, I usually set DefaultDbCachePages=20480 corresponding
> to 80 Mo ram. Application access to only one database. There is up to
> 100 concurrent connexions.

I hope that 20480 is a typo ;)

> The server has 4 Go RAM.
> Should I keep the same value on classic ?

No. The values are per engine instance, and Classic server has one
engine instance per connection whereas Superserver has a single shared
engine instance. You can see this reflected in the default values for
the cache settings in firebird.conf. Superserver can afford a higher
value because you know there is only one engine running.

You haven't answered the most important question still. I have already
mentioned that the 'big win' of classic is that it can better use
multiple CPU cores. The OS can allocate a different core to each
fb_inet_server.exe process (for which you have one per connection +
one additional). Most other performance aspects are a close lose for
Classic. So how many cores does your server have? Quad core (or
higher) generally favours Classic. Single core generally favours
Superserver. Dual core is 50:50. In any case, you should configure a
test environment to ensure you are using the overall optimal engine.

As a 32-bit process, Superserver is limited to 2GB RAM. Classic is
limited to 2GB per connection.

Adam