--- In [email protected], "karolbieniaszewski"
<liviuslivius@...> wrote:
>
>
>
> --- In [email protected], "ramix001" <ramix001@> wrote:
> >
> > I'm trying to get more performance out of my Firebird server. A way to do
> > that is to increase amount of RAM Firebird will use. I'm looking for a
> > reliable method to do that.
> >
> > I started by increasing the DefaultDbCachePages value in firebird.conf to
> > 8192 in Super-Server installations and to 1024 in
> > Classic/SuperClassic-Server installations. But there wasn't a noticeable
> > performance increase. Then I started to increase the DefaultDbCachePages to
> > higher values using this formula:
> > For Super-Server:
> > (Physical RAM in KB / default page size in KB) * 0.04 (4% of total RAM).
> > For Classic/SuperClassic-Server:
> > (Physical RAM in KB / default page size in KB) * 0.005 (0.5% of total RAM).
> > I use this formula only on Windows machines. On Linux this would be
> > counterproductive (I have read). All the databases I use have the default
> > page size of 4 KB and they have no specified cache size (Page Buffers set
> > to 0) only DefaultDbCachePages setting in firebird.conf is being used.
> >
> > With this formula setting in some Firebird SuperServer installations the
> > server process crashes after the fifth simultaneous database connection
> > with the error "Allocated nnnnn page buffers of xxxxx requested". So this
> > formula isn't quite correct.
> >
> > Please tell me:
> > - Does increasing then DefaultDbCachePages really help increasing the
> > server performance?
> > - If it does, are there more things I have to consider to make this formula
> > work properly, e.g. database size, maximum/minimum values, usability with
> > different Firebird versions starting with 1.5?
> > - What functions do settings like FileSystemCacheSize and
> > FileSystemCacheThreshold have in this context?
> >
> >
> > Thanks and best regards
> >
> > Rami B.
> >
>
>
> Hi.
>
> Your formula is wrong
> you must calculated it in this way
>
> ((Free physical RAM in KB without FB started)*0.8 / default page size in KB )
> / count of running databases
>
> eg. you have 8GB RAM but only free is 4GB RAM and 16KB page size and 7
> databases
>
> 4 * 1024 * 1024 * 0.8 = 3355443,2
>
> 3355443,2 / 16 = 209715,2
> 209715,2 / 7 = 29 959 Pages only for DefaultDbCachePages for SuperServer -
> for classic you mast modify formula and add whole conections count in place
> where count of running databases are
>
> Karol Bieniaszewski
>
Hi Karol,
Thanks for sharing. Where does the 0.8 comes from?
