Subject Re: [firebird-support] Re: Classic server vs. Super server
Author Nico Callewaert
Hello !,

Thanks to everybody for the interesting replies ! Lots of useful information.

Many thanks,

----- Original Message -----
From: emb_blaster
Sent: Friday, December 11, 2009 5:12 PM
Subject: [firebird-support] Re: Classic server vs. Super server

> Or is there a link to this information available (in case that was answered
> before already) ?
> Many thanks,
> N.

Hi Nico

you could do a search on messages containing the words "Classic Superserver page size buffers" and found many interestings posts about this. ex.: see this message from Helen in feb 2009.

Page Size 8192 * Buffers 20480

Means a 160MB cache buffer - fatally large for Classic which allocates the same
amount of cache for *each* connection. Probably also exorbitant for SS, unless
you're running a 64-bit server on a 64-bit OS -- it's 10* the default (16 MB for
your page size). Try 128 pages for Classic and maybe 4092 pages for
can move a bit forward or backward from there as your testing progresses to get
a handle on optimal settings for your type of usage.

Actually, "more" doesn't mean "better" with page cache if you don't have oodles
of otherwise unused RAM available. As soon as the cache has to swap to disk,
you've lost its benefit. On a 32-bit OS you have only a *total* of 2 GB
available for an entire process which, for SS, means all of your concurrent

Tip: if you keep the buffers size at 0 in the database header, you can set the
DefaultDbCachePages parameter in the firebird.conf of each respective server, to
avoid having to change the database header each time you switch server models.

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